About

What is this

This guide offers practical advice for parents caring for a newborn.

This isn’t about vague parenting concepts, it’s about concrete day-to-day things like: safe sleep, feeding schedules, transportation, choosing baby formula, breast pumps, things of this nature.

Any claims and recommendations come from reputable sources like
CDC: Centers for Disease Control and Prevention, World Health Organization (WHO) and various government health agencies around the globe. Citations and links to the original reference research papers are always included.

You won’t find any paywalls, affiliate links, or sales pitches here. Operating entirely without profit should assure you, the reader, there are no competing interests or hidden agendas. This is strictly a passion project.

No AI was used in writing this.

Note

I am not a health care professional not I work with infants in my day-to-day job. I am however skilled at reading, understanding and explaining dense research papers. I am a both a parent and I had a vested interest to do the right thing.

You are likely reading the unfinished version of this page, expect some rough edges.

For corrections, questions, feedback, requests and anything else open a new issue or pull request here.

This work is licensed under a Creative Commons Attribution 4.0 International License.

SIDS

Sudden infant death syndrome SIDS is an umbrella term for a child under 1 year of age inexplicably dying in their sleep. In a strict clinical sense what causes SIDS is unknown, but there are several known risk factors and ways to drastically reduce the chance of this happening. In 1994 the US National Institutes of Health launched the “Safe to sleep” public information campaign which encourages safe sleeping practices. This campaign resulted in a decline of more than 50% in SIDS cases in US. Most of the recommendations from health agencies world-wide are based on it.

How common is SIDS

To start with the conclusion: Sudden Infant Death Syndrome (SIDS) is uncommon, following safe sleep guidelines makes it even less common.

In 2022, the risk of being affected by SIDS in the US was 0.042% (42 cases per 100,000 live births).
In Europe the data from 2011 to 2018 shows a probability of 0.015% (0.15 cases per 1000 live births).

To be precise:
Any sudden unexpected infant death (SUID) can be attributed to either SIDS or to suffocation in bed. Since determining the exact cause of death is often impossible a significant proportion of sleep-related suffocation cases caused by unsafe sleep practices end up classified as SIDS. This explains how causes of SIDS are fundamentally unknown, yet the danger can still be heavily mitigated by adhering to safe sleep guidelines.
CDC SUID rates in US 1990-2024
CDC report SUID 2020-2024

To further highlight the importance of adhering to safe sleep guidelines:

Infants who were not placed to sleep supine [on their back] had nearly 2 times the odds of sleep-related suffocation … The use of soft bedding was associated with a 16-fold increase in odds of explained suffocation (aOR = 16.3, 95% CI: 5.0–53.3) and 5-fold increase in unexplained infant death, compared with no soft bedding use (aOR = 5.0, 95% CI: 3.2–8.0). Infants who were not placed to sleep in a crib, bassinet, or portable crib had 4 times the odds of explained suffocation death compared with infants who slept on an approved sleep surface. PMC9942004

SIDS risk by month

Babies between 0 and 4 months of age have the highest risk of SIDS/SUID. In US during 2011-2013 between 76% and 86% of SUID cases occurred from 0 to 4 months of age. 90% of all cases occurred before the 6-month, and becomes uncommon after 8 months.

With regard to SIDS specifically, 90% of cases occur before an infant reaches the age of 6 months. SIDS peaks between 1 and 4 months of age and is uncommon after 8 months of age Pediatrics (2022) 150; DOI 10.1542/peds.2022-057991

NOTE: The term “SIDS” applies only to infants younger than 1 year of age. As your child grows older they become more resilient to dangers like positional asphyxiation, but they still can get entrapped in the bedding structure or loose bedding. PMID: 10520608

Even after one year of age you should assess the risks whenever changing the sleeping arrangements.

How to prevent SIDS

The best way to reduce the risk of SIDS is creating a safe sleep environment for your baby. SUID/SIDS is rare, following safe sleep practices significantly lowers the risk even further by a large amount.

Below is a detailed overview of safe sleep practices, complete with supporting evidence and citations from various research papers. For a lengthier more technical review see: Updated 2022 Recommendations for Reducing Infant Deaths in the Sleep Environment published in Pediatrics (Vol. 150 e2022057990)

Place baby on their back for sleep

Young babies can not roll or reposition by themselves. Placing them on their back (supine position) ensures their airways are straight and the parent does not accidentally obstruct their breathing when putting them down. Additionally, the supine position minimises the risk of rebreathing previously exhaled air that is depleted of oxygen.

Once a baby gains the ability to roll on their front (3-6 months) they might choose to sleep on their front, you don’t need to re-set them to their backs. If the baby got into a position by themselves they should be able to move away from it if they need to as long as they are not swaddled.

• The above applies for all sleep times including naps.
• Insist that all caretakers put the baby to sleep in the supine position.
• A swaddled baby should never be put sleep on their front. See the chapter about common swaddling mistakes.

Use a firm flat mattress

When the mattress is to soft the baby’s face can sink into it and cause rebreathing of oxygen depleted air.

Fortunately the majority of developed countries heavily regulate baby sleeping surfaces. For example in the EU the EN 16890:2017+A1:2021 requirement for “Mattresses for cots and cribs” amongst other hazards, specifically tests the mattress hardness. It is illegal to sell baby sleep products on European markets without passing this certification.

• For cots or bassinets brought in developed countries, regulations exist that ensure the mattress is both firm and breathable enough to be safe.
• Avoid antique or DYI mattresses and baby sleeping surfaces. These did not pass any regulatory testing and also might use prohibited/dangerous materials like formaldehyde or led paint.
• In case you need to check if a mattress is firm enough for a baby the following testing methodology was published in the Australian and New Zealand Journal of Public Health.
• Infant car seats and similar baby containers are not designed for unsupervised sleep.

Do not bed share

There is no such thing as safe cosleeping.

54% of infants in the SUID Case Registry were surface sharing at the time of death. Findings from a meta-analysis showed surface sharing was associated with an almost threefold risk of SIDS. Surface sharing is associated with an increased odds for both sleep-related suffocation and unexplained infant death (adjusted odds ratios: 2.5 [95% confidence interval (CI) 1.1–6.0] and 2.1 [95% CI 1.4–3.2] respectively). Pediatrics (2024) 153 (3): e2023061984

Dangers of bed sharing include:

• A sleeping adult can accidentally roll over the baby suffocating them.
• The baby might get tangled on loose bedding, pillows or blankets.
• Risk of baby falling on the floor.
• Adult mattresses (even hard ones) are often too soft for a baby and pose suffocation hazards.

Many people chose cosleeping for the practical advantages it offers, but the research is clear: the safest place for a baby to sleep is in their own bassinet in the same room as you.

I highly recommend buying a “sidecar bassinet” which features a removable side-railing. Installing you next to your bed provides easy access to the baby, delivering the convenience of co-sleeping without any of the risk. Because a bassinet is designed specifically for newborn sleep it provides a firm sleeping surface, removes any risk for entrapment and provides a physical barrier preventing adults from accidentally rolling onto the child.

Sharing the room is recommended, it is both convenient and allow you to check on your baby during the night.

Avoid crib clutter

Keep all soft or loose items out of your baby’s crib. Loose blankets, pillows or plush toys pose a suffocation risk.

Are crib bumpers safe?
Crib bumpers pose the same risks as items mentioned above and their sale became prohibited in the US since 2022.

Simply use a fitted sheet over the mattress and swaddle your newborn in a weather appropriate blanket, that’s it. If you don’t want to swaddle a sleeping bag can be used.

Avoid secondhand smoking

CDC classifies second hand smoking as one of the primary causes of SIDS.

Canada’s health department estimates that 14-16% if all SIDS related deaths could be prevented by eliminating second-hand smoke exposure. Source: Canada’s health department on tobacco and SIDS

Prevent overheating

Young babies have poor temperature regulation, they loose heat quickly but also overheat easily.

You can tell if baby is overheating if they have sweaty back of their neck and their cheeks flush red. In more severe cases their breathing will become more rapid and laboured. Research shows that babies are safer being slightly cooler than being too hot. A baby that is too cold will wake up and their cheeks and chest will be cold to the touch. Do not rely on your baby’s hands or feet to tell if they are too hot or cold. Their developing circulatory system means their extremities will usually feel much cooler than the rest of their body

The ideal temperature range for sleep as per NHS safe sleep guidelines is between 16 and 20 degrees Celsius.

Babies should never sleep in next to a radiator, in direct sunlight or any other direct heat source. Hats or head covers should not be used during sleep.

Pacifier use is encouraged

While the exact mechanisms are not yet clear, several meta-studies from 1993 onwards show between 30% and 50% SIDS risk reduction attributed to pacifier use at the onset of sleep. Source: Investigation-of-sudden-infant-death-syndrome The American Academy of Pediatrics safe sleep guidelines advise using a pacifier at the start of sleep; You do not need to reinsert the pacifier if it drops out after your baby falls asleep.

Note that an early introduction of a pacifier can have negative effects on breastfeeding. See the chapter about how pacifiers can influence breastfeeding

Breastfeeding

Human milk has a protective effect against SIDS.

A meta-analysis conducted by Hauck et al. (published in Pediatrics) shows that babies who are breastfed for any amount or duration have a reduced risk of SIDS by roughly 50%. The protective effects increase for exclusively breastfed infants who have up to a 73% reduction in risk.

Breastfeeding is protective against SIDS, and this effect is stronger when breastfeeding is exclusive. The recommendation to breastfeed infants should be included with other SIDS risk-reduction messages to both reduce the risk of SIDS and promote breastfeeding for its many other infant and maternal health benefits. Pediatrics 2011 Jul; DOI: 10.1542/peds.2010-3000

Do not use baby containers for sleep.

A baby container is any piece of baby equipment that holds an infant in a fixed position or at an angle. Typical example are infant loungers, baby nests, pods etc. Several products in this category will feature in their marketing material a sleeping baby or advertise themselves as a sleeping device. Some of them even go as far as to claim they reduce the risk of SIDS when in fact it is the opposite.

Highlighting this point, Health Canada issued an urgent recall for several baby nest products in this category specifically because they pose a severe entrapment hazard risk of entrapment. A crib, cradle, or bassinet are the only safe environments for an infant’s unsupervised sleep as they feature a firm flat sleeping surface and stiff upright sides.

Infant car seats also fall into the category of baby containers, see our chapter dedicated to car seat sleep safety.

Annex: SIDS and predatory advertising:

SIDS is very scary (I am reliving the stress even when writing about it) and there are actors trying to capitalize on your fears.

I remember receiving many ads for gadgets that claim to prevent it: oxygen monitors, inclined sleepers, smart baby monitors with breathe rate detection and all other kinds of similar snake oil. These will be advertised as “the definitive preventative measure”, but when inspecting the fine-print you are guaranteed to see keywords like “for comfort” or “fitness tracker” or “not a medical device”.

None of these passed any sort of certification. The ads can claim anything but if something is legally classified as and “infant lounger” (as is the case for the baby nests) it can skip all the testing that is legally required for baby sleep products.

At best, they do nothing, at worst they are actually putting your newborn in danger. For example did you know that oximeters can cause skin burn if not used correctly?

There are currently no commercially available products that can prevent SIDS.

There are of course medical cases where special monitoring products are needed, but in this situation an actual medical professional will tell you exactly what to use, where to rent it and how to use it correctly.

Swaddling and sleeping bags

Swaddling has two purposes: It keeps your baby warm, and helps with the baby’s startle relexes.

Since loose blankets are not recommended under safe sleep guidelines, use a swaddle or sleeping bag as a safe alternative for warmth.

Babies under 6 months will often move their arms during sleep, this is caused by the Moro reflex and is normal young infant behavior. However, their own movement can wake them up. Restricting their range of movement generally make a newborn move comfortable and makes them sleep better.

Swaddling is optional and brings no extra benefits other than comfort, you can use a sleep sack as early as you want. For example my daughter hated being swaddled and kept wiggling herself out, we transitioned to a swaddle sleep sack during first or second week after arriving home.

Swaddling mistakes

A swaddled baby must always sleep on their backs!

Any infant younger than 1 year should be placed to sleep on their back to avoid re-breathing and positional asphyxiation but this is especially important for swaddled babies. Swaddled babies can’t move their arms in order to push and reposition themselves drastically increasing risk of re-breating or positional asp

Stop swaddling when baby shows first signs of rolling

Infants typically begin attempting side-to-side rolling between 4 and 6 months of age. If a swaddled infant rolls into a prone (face-down) position, restricted arm movement prevents them from rolling back, creating a high suffocation risk. At this stage you should transition to a sleeved or sleeveless sleeping bag that allows free arm movement.

Both safety rules above also apply to “swaddle sleep sacks” or anything that restricts arm movements. Once a baby can “get face down” limiting their arm movement becomes a SIDS risk factor.

Do not restrict leg movement

Do not wrap the legs. Baby’s legs and hips should have full range of motion. Restricting leg movement was a common practice in the 19th century and is still common in some parts of the world, however this practice has been shown to cause hip-dysplasia (abnormality developed hip joint).

Traditional swaddling, which implies restrictive immobilisation of the infant’s lower limbs with the hips in forced extension and adduction, has been shown to be a risk factor for Developmental Dysplasia of Hip (DDH). PMC8688658

Traditional swaddle

Versatile and cheap but requires the most practice to master.

Around the chest the swaddle should be tight, but not as tight as to restrict breathing. Two or three fingers should fit between baby’s chest and the swaddle, this is known as the “two finger rule”. Do not wrap the legs.

An excellent video tutorial Swaddle Your Baby Like a Pro: Pediatrician Tip from The Doctors Bjorkman. (This channel is a great general learning resource by the way)

Velcro swaddles

Very similar to a traditional swaddle but much easier to use. Besides requiring less dexterity, it does not allow the caretaker to use it incorrectly. Unlike old-school swaddles, velcro swaddles come in different sized for different baby height and weight.

Swaddle sacks (arms-up)

These are a middle of the road option. They provide enough restraint to prevent the Moro reflex from waking up the baby, but they still allow some level of movement for babies that do not like being fully restrained.

In our personal case this option worked best: my daughter hated being motion-restrained and had a strong preference to sleep with her hands up. This looks more like a sleeping bag, but it is still a swaddle and use should be stopped when baby shows signs of rolling.

Some models labeled as “transition bags” allow the option to have one or both arms out of the sleeping bag. This is useful for accommodating your baby to standard non-swaddle sleep sack.

Sleeping bags

Transition to these when your baby starts showing signs of rolling on their own. At this stage (usually 4-6 months) free arm movement is important for safety and the Moro reflex will mostly disappear.

These can be used up to any age.

TOG rating

A sleep sack or swaddle will normally come with a TOG rating (Thermal Overview Grade). This should tell you what the ambient temperature this sleep bag was designed for, higher the TOG the warmer the fabric.

This is a chart from ergopouch of different ratings for different ambient temperatures.

While a good point of reference there is no “official” chart telling you which TOG to use for each ambient temperature. Different manufacturers will publish their own charts, which will slightly differ. Treat the TOG rating as a general guide, not a strict rule.

Check baby’s chest and back to gauge if they are too cold or too warm and adjust accordingly.

Mattress firmness test

This test determines if your mattress is firm enough to prevent re-breathing. If at all possible children especially under one year should sleep on certified baby sleep products, which makes this test unnecessary.

That said there are cases where being able to tell if a mattress is suitable for infant sleep can be useful. The most common case would be transitioning to a montessori bed, which require adult-size mattress.

Instructions on how to perform this tests can also be found here Infant sleep safety: testing for correct mattress firmness. on the Education Standards Board(ESB) of South Australia webpage.

This methodology was submitted in Australian and New Zealand Journal of Public Health“ in 2012 by Ronald L. Somers

According to the author, this substitute matches to a high degree the results produced by a specialized device used in “The German case-control scene investigation study on SIDS” by Schlaud M et al.
I can’t find the original Schlaud paper, but it is quoted in A firm recommendation measuring the softness of infant sleep surfaces by Sheena H. Gillani et al.

Schlaud et al. found that 27 of 41 (67%) scene investigation mattresses had > 14.5 mm indentation
...
a surface with an indentation of > 14.5 mm was significantly associated with risk of SIDS

In essence:

• The surface area of the DVD paired with the weight of the milk cartons (2,325 g) simulate the weight distribution of a baby’s head.
• The thickness of a DVD is 1.2 mm, a stack of 12 DVDs is 14.4mm in height. Which matches what was assessed as the maximum safe mattress indentation in the by Shlaud M paper.
• Hence: If the 12 DVD stack fully sinks into the mattress it can be concluded that the mattress is too soft and should not be used for infant sleep.

Pacifiers

Deciding if you should introduce a pacifier and when to do it is highly situational.

Yes, offering a pacifier before sleep is recommended by the safe sleep guidelines, but the same public health officials acknowledge that introducing one too early can have negative effects on breastfeeding (if this is one of your goals).

In this chapter I will outline the key factors at play, so you can decide for yourself what to do.

In addition, I highly recommend reading the Recommendations for the use of pacifiers from the Canadian Paediatric Society as it treats the topic in much more depth.

Safety and general considerations

Independently of pacifier type and when it is introduced there are some safety rules that must be followed.

Safety

• The pacifier shield should be large enough that it cannot be entirely pulled into the baby’s mouth. Using a pacifier with an undersized shield poses high choking risk.
• Pacifiers degrade with use. Before offering, briefly inspect for cracks or parts coming loose. if you see any structural damage discard it. (We had 2 pacifiers cracking during 1 year).
• Do not attach the pacifier with cords or ribbons to the baby’s clothes or bed during unsupervised sleep. This poses strangulation risks.
• Never forcibly introduce a pacifier into a sleeping baby’s mouth.

The general considerations are mostly about what to look for when buying it. However, it is worth noting that each baby has their own preferences, you can’t force a baby to accept a specific pacifier.

General Considerations

• Each pacifier comes with a manufacturer’s age recommendation (0-3, 3-6, 6-12) on the box. If you are concerned about the sizing these are some rules of thumb.
  • A pacifier that is too big will cause gagging, excessive drooling and its shield will be resting on your baby’s nose.
  • A pacifier that is too small will leave imprint marks on the baby’s cheeks and nose. The baby will have difficulties holding it in their month and is likely to spit it out.
• Prefer soft silicone for the pacifier tip.
  • A pacifier made from tougher materials creates more strain on mouth muscles.
  • Latex can cause allergic reactions and is prone warping when sterilizing.
  • Most silicone pacifiers from reputable brands are made of BPA-free food grade silicone (they will brag about it on the box).
• Avoid unnecessary weight, like plastic decorations on the shield. The extra weight makes it harder to keep in the mouth thus less comfortable.
• The shield should have perforations for airflow.

Breastfeeding and round pacifiers

Suction on a pacifier is mechanically different from a breast. To establish an effective breast latch, your baby needs to shape their mouth and tongue in a specific way that is different from the way they suck on a pacifier Introducing a pacifier too early can cause your baby to get confused and appear to “forget how to latch”, this is usually referred as nipple confusion

If your goal as a family is to breastfeed, the standard recommendation lactation consultants is to introduce a pacifier only after establishing strong breastfeeding patterns (usually 4-6 weeks).

On the other hand, if you are bottle-feeding you can introduce the pacifier from directly from birth. Extracting milk from a bottle demands less skill and effort from a newborn. In addition, a wide selection of bottle shapes exist, if one bottle teat does not work for any reasons you can easily try another. This is why you will sometimes see the term “pacifiers for bottle-fed babies” thrown around: with nipple confusion not being a relevant factor, the manufacturers can focus their design efforts elsewhere.

For breasted babies you should opt for pacifiers that:

• Are symmetrical on all axes.
• Have a rounded tip and a gradual slope.
• Have a wide base.
• Are made of soft silicone.

These designs try to emulate the shape of a nipple, hence should help prevent nipple-confusion. Ninni-co and Dr Brown’s pacifiers seem to be a popular choice in this category (the exact brand does not matter, the shape does).

Example of good shapes:

Avoid pacifiers with a significant “bulb” on the tip and shallow bases, these are sometimes referred as “cherry shaped”. As far as I understand they are easier for the baby to keep in their mount, but they can cause a shallow latch.

Example of bad shape:

Anatomical pacifiers and moth development

Anatomical pacifiers (sometimes called orthodontic) style of pacifier is advertised as the better option in supporting mouth development and preventing misalignment of the teeth. They are asymmetrical and feature a narrower base with a wider tip.

However, there is little to no scientific evidence supporting this claim. The only relevant study I could find on the subject states the opposite.

According to Adair et al.: “No clinically significant differences were found between 24- to 59-month-old users of conventional and orthodontic pacifiers with respect to sagittal, vertical, and transverse occlusal relationships.”

On the flip side there seems to be consensus among pediatric dentists that early weaning and limiting the hours of use per day has the highest positive impact on preventing mouth and denture development issues.

For example The American Academy of Pediatric Dentistry in their policy from
recommends weaning at 18 months with a hard cut-off at 36 month to avoid crossbite, overbite and dental malocclusion.

If mouth development is one of your concerns early weaning and limiting use is the better option.

When to wean off

There are several recommended ages when to wean off the pacifier. None of these except for the last one (3 year mark) are “set in stone”. The correct timing will depend on your particular case.

• 6-7 months: By this age most babies can self-soothe without a pacifier. At this age they have lower emotional attachment towards things (pacifiers included) making the weaning process easier.
• 12 months: The American Academy of Pediatric Dentistry states that prolonged pacifier usage after one year of age can increase the risk of acute otitis media (ear infections). Sources AAPD guidelines , Warren et al. and Jackson et al.
• 18 months: Pacifier use after one year and a half was linked to crossbite, overbite and improper teeth alignment.
• 36 months: Using a pacifier after the age of 3 can cause long-term dental issues which require medical intervention to fix. This age is “firm cut-off” point.

In our personal case, we used the pacifier only during sleep and had no complications, neither with ear infections nor with misaligned teeth. Since our daughter used it rarely she did not develop emotional attachment to it and simply stopped asking for the pacifier at around 16 months of age.

Regarding preterm babies

There is a special consideration when it comes to preterm babis that spend time in intensive care after birth. Your neonatologist will most likely suggest introducing a pacifier directly after birth.

When a baby’s moth muscles are not sufficiently developed to extract milk by themselves they will initially receive nutrition via a gastrointestinal tube. Removing the GI tube is one of the priorities on the neonatologist’s list. By introducing a pacifier early,

• The baby gets to exercise their mouth muscles, eventually developing the ability to feed by either breast or bottle.
• Sucking on a pacifier mitigates the risk for the baby loosing their sucking reflex.
• The soothing effects provided by pacifier helps with pain management during procedures and general emotional regulation.

You can read more on the topic here.

Warning

There is no advice in this section. The goal is only to provide some context for people that are in that situation and are wandering what’s the reasoning behind their doctor’s decision.

Infant car seats

While infant car seats function the same, different regulations and testing standards exist across distinct regions of the world. I’ll be focusing primarily on European Union here. This chapter will include links to different seat models, these are included as examples for clarity and are not product endorsements.

Sizes and groups

Car seats are categorized in broadly 3 groups:

Warning

Child’s “age” does not matter and is included just for estimation purposes. What actually matters is baby’s height and weight. When your baby exceeds the maximum height or weight (whichever comes first) the car seat stops providing adequate protection and has to be changed. One of the most common errors resulting in injury is using an inappropriately sized car-seat. Always check the manual to ensure your child fits correctly.

I say “broadly” because some models are size-adjustable and can cover multiple groups.

• Bucket seats (group 0 exclusively): These are rear-facing and can be used until approximately one year of age. This is the only category that supports detaching the seat from the base while the child still strapped in and mounting the seat onto a 3-in-one modular travel system. It is a good option if you favor portability and not waking up the baby when the car-ride ends. For example Maxi Cosi 3 in 1. If you are considering a 3-in-1 travel system I encourage you to read about sleeping in a car seat.

• Convertible car seats (both group 0 and 1): Opposed to the bucket seats described above these have a much larger usage span and generally last from birth to 4 years. They are bigger, heavier and not designed for portability (you can’t detach this seat from the base with the baby strapped in). This category support both forward and rearward facing positions and generally feature a rotating base for easier loading and unload of the child. For example Cybex Sirona T i-Size is such a seat.

• Booster seats (both group 2 and 3): Are modular and change configuration based on child’s age: starting with 5-point-harness + high-back-booster and progressively transition into high-back-booster + car's belt and no-back-booster + belt. An example of a seat in this group BeSafe Flex FIX. This category of seat is exclusively forward facing, does not rotate and is attached directly to the car’s car’s ISOFIX mounts. Usually much cheaper than seats of group 0 and 1.

• Evolutive car seats: These models cover all three groups and can be used from birth until your child can use the car’s seatbelt. The ergonomics sometimes suffer in favor of adjustability (depends on both the seat model and the child). This is by far the most cost-effective option. Chicco EVO i-size is a seat of such type.

To my knowledge most common route is to get a convertible car seat (birth to 4 years) and transition into a group 2/3 seat later.

Standards

• R129 also known as i-Size is the latest safety standard at the time of writing (2026). Any infant car seat sold in the EU since 2014 is required to have this certification. To obtain it, different seat models are tested for frontal(50 km/h), side(30km/h) and rear(30km/h) impacts. More about testing methodology in this article.
• R44 is the older mandatory standard. These car seats can still be legally used, but not sold by retailers. Unlike R129, these car seats are not rated for side-impacts. This is one of the main reasons they are being phased out.
• Swedish plus is a voluntary test manufacturers can undergo. It mostly focuses on frontal collisions measuring the forces applied to the neck and spine in case of an accident. Premium brands will have this certification in addition to the mandatory R129.
• ADAC is the german counterpart to the Swedish plus test. These tests are performed independently without manufacturer opt-in (the organization itself chooses what models to test). Evaluation results can be found on their official page. ADAC results for 2025

These accreditations will be mentioned on seller’s web-site or are present as a sticker on the seat itself.

Installation

ISOFIX

ISOFIX is a standardized European system for securing child car seats. It uses rigid connectors attached to the vehicle’s chassis for a more secure fit. These connectors are located on the backseats of the car, on the lower side of the backrest. All cars sold in europe since 2012 are required to have ISOFIX mounts, but even older cars are likely to have them.

Infant car seats can be installed either onto a dedicated base or secured using car’s 3 point harness.

The base is attached to the ISOFIX mounts and seat clicks into the base. Generally using a base allows you to rotate the seat by 90 degrees for loading and unloading your child. In my opinion the extra convenience of being able to rotate the seat is worth the extra cost of purchasing the base.

The ISOFIX mounting option is considered safer, as it eliminates a majority of common installation errors and reduces car-to-car variability.

Position in the car

The rear middle seat is the safest location in the car for an infant car seat, while the front passenger seat is the most dangerous.

Overall, the rear (2nd row) seating positions have a 29.1% (Univariate Analysis, p < .0001, OR 1.29, 95% CI 1.22 - 1.37) increased odds of survival over the first row seating positions and the rear middle seat has a 25%

Journal of Safety Research V39

Regulations differ from country to country, but as a generality infant car seats are not legally allowed to be installed in the front of the car besides special cases (for example car does not have rear seats or all rear-seats are occupied by other children).

If the infant car-seat is installed in the front row of the car, in the majority of cars the car’s seat must be moved all the way back and the passenger air-bag is manually deactivated. A deployed airbag can propel a rear-facing infant car seat into the backrest potentially causing serious head and spine injury.

Warning

Correctly installing the infant car seat in the front row differs from car to car. Your car’s manual will have a chapter dedicated to this, you must read it and ensure it is done properly. Do not rely on generalities for this step.

The airbag must be turned off via mechanical means (usually a key on the side of passenger’s dashboard). Do not rely on software deactivation for this!

I recommend watching this video for more details on front installation.

Installing in the back is much less complicated, generally the side-airbags of the car should remain engaged, but always consult your car’s manual to ensure correct installation.

Forward or rear facing orientation

Babies between approximately 0 and 15 months must be seated rear-facing, failure to do so will result in a fine (beside it being a bad idea).

In EU children over 15 months are allowed to sit forward facing but is the less safe option. Based on this Swedish report from all fatal injuries from 1992 to 2024, 47% of fatalities could have been avoided if the child were restrained in a rear-facing car seat. Sweden has been one of the main advocates for rear-facing seating and their recommendations advocate for exclusive rear-facing seating as long as possible, at least until age of 4/5. The Folksam safety rating program from the same conference goes into some details.

Infant car seats in group 2/3 are almost exclusively forward facing. There are some group benders like the BeSafe beyond that allows rear-facing seating until approximately 6 years (125 cm height and 22kg), but it’s the only example so far. At this age children stop having enough legroom in a rear-facing position, and they weigh too much for the seat effectively manage the downwards rotation, so forward-facing sitting position is the only feasible option.

Warning

Never travel with your child facing sideways. It is extremely unsafe and illegal. I saw a staggering amount of people swivelling a car seat so it faces side window.

Sleeping in the car-seat

Is it safe to sleep in a car seat?
While the answer is quite straight-forward the guidelines seem to be in contradiction with each other:

According to safe sleep guidelines sleeping in baby containers is not allowed, and an infant car seat is a baby container, so no?
At the same time nhs advices taking breaks every 2 hours and not letting the baby sleep in a car seat that longer than necessary, so yes?.
Also why does it matter if the car is moving or not?

So what’s the danger and are you supposed to wake a child that fell asleep in a car seat?

The main risk of sleeping in a car seat is positional asphyxiation. The baby can slump forward or sideways obstructing their airways causing difficulty in breathing. This is an example of a dangerous position: Group 1 and 2 car seats are designed for the baby to sit in a semi-reclined 45-degree angle. Sitting at this angle provides the best protection in a crash while limiting the probability of positional asphyxiation during limited use. Research shows that the more time a newborn spends in the same position the higher the probability of positional asphyxiation.

The secondary risk of sleeping in the car seat is overheating. These seats are made of thick materials which retain heat. Excessive heat is one of the risk factors for SIDS considering the underdeveloped self-cooling mechanisms of a young baby.

Both of these risks can be managed by active adult supervision. So yes, a child can sleep for a short duration (1-2 hours) during trips while an adult is monitoring their position.

Why should you remove them from the car seat after the trip has ended: Notice that the actual seats in cars are tilted slightly backwards. The engineering of infant car seat takes that into account the car’s natural seat inclination and compensates for it. Placing a baby car seat on a flat surface increases the sitting angle and makes slumping much more likely. This also explains why 3-in-1 travel systems are generally considered safe for supervised sleep only when attached to a compatible base. The base is designed to offer an appropriate sleeping angle and there is an adult keeping an eye on the baby.

Warning

A car seat should never be used for unsupervised sleep.

Even positional asphyxiation aside, there are multiple reports of babies waking up and entrapping themselves on the belts, falling from elevated surfaces (in case the car seat is placed on a table) or injuring themselves by tumbling sideways together with the seat, or people forgetting a sleeping baby in a hot car.

Generally a bad idea. You should move the baby onto a suitable sleeping surface after the car ride has ended.

This is good blog post on the topic of car seat sleep safety

About used car seats

Used car seats should generally be avoided for these 2 reasons:

Infant car seats are rated for exactly one crash, and should be discarded after an accident. This is why you are not allowed to return or exchange a car seat after it exited the shop. Retailers can’t resell it as they can’t prove the seat was not involved in a crash.

Pro-tip: Brick and mortar shops will often have “showroom seats” that you can lease for a short duration. This allows you to test if the seat fits in your car and if your child sits conformably, before commiting.

Also, keep in mind that infant car seats expire—typically 6 to 10 years after they’re made. You can find the exact date on a sticker attached to the seat. Over time, heat and UV rays break down the plastic; even if no damage is visible on the outside, the internal foam (EPS) can degrade, failing to provide proper protection during a collision.

Purchasing a secondhand car seat requires you to rely on the seller’s honesty regarding its accident history while also verifying that the seat hasn’t reached its expiration date.

Extra safety features

This section goes through the distinct safety features different models of infant seats might have.

In truth, few people should care about this. To get the mandatory R129, any car-seat will be tested and is guaranteed to offer adequate protection. Some more premium brands might have multiple redundant protections, in case one system fails, the other one picks up the slack, but some skepticism is required: more addons does not necessarily mean safer. The only real way to know if a seat is safer than the other is via ADAC or Sweedish Plus or any other independent testing organization.

This section goes into some details on how this extra safely features work and what is their purpose.
Infant car seats have to manage three primary safety aspects: side impact protection, downwards rotation and ensuring the child is seated correctly.

Side impact protection

The R129 simulates a side-impact collision at 24km/h and benchmarks the forces acting on child’s head, neck and torso.

Virtually all modern baby car seats will feature a rigid outer shell made out of molded plastics and sometimes a steel reinforcement. Underneath it is a layer of shock absorbing materials, usually polystyrene and/or polypropylene.

In addition to this, some of the more premium brands will offer either a SIP or a pop-up crumple wings as a redundancy. A SIP (side impact protector) is detachable airbag that is mounted to the baby seat itself, one example of a seat featuring a SIP is BeSafe Beyond.

A crumple wing is an extendable wing that absorbs shocks and transfers it to seat’s shell (similar to a SIP), one example is the Cybex sirona.

Downward rotation

This is concerned with frontal impacts also tested by R129 at 50km/h.

In a sudden stop, inertia pushes the car seat forward and causes it to rotate. Once the vehicle stops completely, the seat may rebound, flipping back toward the car’s backrest. This behavior is called “downwards rotation” and “rebound” respectively.

The ISOFIX mounts or belts (depending on the installation mode) will do most of the heavy lifting here. A majority of models in group 0 will feature some sort of anti rebound bar. In case there is slack on the belts or the base is not correctly installed (and downwards rotation is not managed correctly) the anti-rebound bar acts as a barrier between the child and the backrest of the car.

The load-leg of the base serves a similar purpose, but instead of managing rebound, it ensures the seat does not rotate forward by anchoring it to the floor of the car.

A top tether functions the same as a load-leg. Instead of anchoring the seat to the floor of the car (push), it uses a third anchorage point that connects the top of the infant car seat to the car via an extra belt (pull).

Five point harness

The five point harness is not mandated by R129.

This type of harness prevents what is colloquially called “submarining”, where the child’s body slides down, causing the belt to move from their rib cage onto the softer abdominal area (potentially leading to internal injuries on emergency breaking).

By virtue of being more restrictive the five point harness does not allow incorrect seating positions and also prevents older babies from “escaping from the straps”.

Nipple confusion

Nipple confusion refers to a baby’s feeding challenges when transitioning between a breast and a bottle, or their difficulty latching onto the breast after being introduced to an artificial nipple.

Nipple confusion generally shows up in two ways:

Type A - Difficulty latching

This occurs in younger babies who start having difficulty latching after the introduction of a pacifier or bottle. In order to establish an effective breast latch, your baby needs to shape their mouth and tongue in a specific way which is different from the way they suck on a pacifier or from the bottle. Premature born babies are more susceptible to struggle with latching.

Type B - Bottle preference

This occurs in older babies which already know how to latch but develop a preference for bottle feeding. Bottle feeding requires less coordination, the flow is usually faster and the baby does not need to wait for the milk let-down. Access to “easy milk” makes some babies either hesitate or straight-up refuse to breastfeed. This is often referred to as “bottle preference” or “flow preference”.

Infant feeding is complex act both for the mother and the baby.

In our study, 83.5% of mothers reported difficulties, indicating the need for early identification and intervention. Similar results were reported in a survey by Gianni et al. [27,28], who found that 70–80% of women experienced breastfeeding difficulties, such as nipple pain, feeling inadequate, or fatigue.
doi: 10.3390/nu17061070

Initial feeding challenges tend to compound over time and become harder to address with time. For example:
A baby suffering from a mild-case of tongue-tie struggles to transfer milk efficiently, parent introduces bottle supplementation to address the low weight gain, the baby is able to nurse better from the bottle developing a preference for it. Eventually the tongue-tie is diagnosed and treated but by this point the bottle preference is firmly established making continued breastfeeding unlikely.

When struggling with breastfeeding the best course of action is to contact a IBCLCs (International Board Certified Lactation Consultants) or a midwife as soon as possible. Minor early tweaks can have large impact in the long term, if addressed straight-away.

Signs of nipple confusion

Signs of nipple confusion fall into two main categories: Inability to latch and frustration at the breast.

Inability to latch

The infant is attempting but failing to establish efficient milk transfer. This can also stem from other factors like poor breastfeeding position or other factors for breast refusal.

• Thrust their tongue up while they’re sucking, which can push the nipple out of their mouth.
• Fail to open mouth wide enough resulting in a shallow latch.
• The baby cannot maintain suction and repeatedly loses their grip on the areola.
• Changes in sucking patterns during breastfeeding

Short and impatient breastfeeding sessions.

The baby is getting frustrated and angry at the breast. This can also stem from low milk supply, a stressful prior breastfeed experience for the baby or even baby’s temperament.

• Biting on the nipple (which besides other things, can signal frustration)
• Crying during feeds and giving up on the breastfeeding session quickly.
• Arching their back or pushing the breast away during breastfeeding but not when offering the bottle.

How to fix nipple confusion

• Wait until breastfeeding is well established (roughly 4-6 weeks) before introducing a bottle. These initial weeks allow the baby to master the latch and the monther to establish the milk supply. Consider alternative supplementation options if supplementation is required.
• Lactation consultants often advice waiting 4-6 weeks before introducing a pacifier. This advice is based on the old WHO policy: see chapter on pacifiers and nipple confusion
• Use paced bottle feeding. This technique (an evolution of the Kassing method) mimics the rhythm and flow of breastfeeding. Its primary goal is to support breastfeeding while offering additional benefits such as reducing gas and reflux.
• Use a slow flow bottle. See baby bottles for a guide on how to choose a baby bottle.
• Create a calm environment for breastfeeding sessions to help the baby form a positive association with nursing.

Is nipple confusion real

Likely yes. Bottle introduction can cause some babies to develop a poor latch or bottle preference.

First off the term “nipple confusion” (nor any of its synonyms) is not a medical condition and lacks a formal definition so it’s not something a doctor can diagnose. So while it’s technically true that it “isn’t real”, whether artificial nipples actually have a negative impact on breastfeeding is still being actively investigated by science.

Studies show that bottle feeding is tied to a shorter overall breastfeeding period. However, critics point out that these studies fail to prove cause and effect. For example, the introduction of a bottle into the infant’s feeding regimen may reflect a parental intention toward early weaning. Another example is that a baby who is already struggling to breastfeed is more likely to be given a bottle in the first place.

The main findings of this study suggest that infants who use pacifiers and/or are bottle-fed have a higher frequency of indicators of BF difficulties when compared with those who do not use these devices.
…
Additionally, infants receiving mixed feeding (breast and bottle) position the tongue as a piston when sucking the breast, a behavior that is common when sucking the bottle, but not when sucking the breast (represented by undulatory movements), emphasizing the muscle pattern change after the introduction of the bottle.22
DOI 10.1016/j.jped.2017.10.005 (Jornal de Pediatria 2018)

Studies have shown that sucking patterns developed by infants in the first 2–4 weeks of life are “path-dependent,” and that early exposure to the mother’s nipple or bottle can lead to the solidification of oral muscle memory, with babies accustomed to the mother’s nipple being reluctant to use a bottle, and babies accustomed to bottle feeding refusing to be fed from the mother’s nipple.
DOI:10.26689/jcnr.v9i5.10652 (Journal of Clinical and Nursing Research, 2025)

The consequences of offering artificial nipples to breastfed infants are mostly negative and associated with the newborn, such as early weaning, refusal to breastfeed, impaired suction technique, incorrect latch-on, interference with orofacial development, and interruption of EBF. Reduced crying and newborn soothing are positive outcomes of the use of artificial nipples during breastfeeding. DOI:https://doi.org/10.7440/res64.2018.03

Historically, researchers have grouped all artificial nipples together under the assumption that any exposure threatened the breastfeeding relationship. However, more recently a distinction has emerged between bottle nipples (nutritive sucking) and pacifiers (non-nutritive).
New research rejects the claim that pacifiers cause nipple confusion.

Do pacifiers cause nipple confusion

Unlikely.
While contested, the current scientific consensus is that pacifiers do not lead to the early cessation of breastfeeding.

Historically WHO and the UNICEF, recommend avoiding use of pacifiers in term infants who breastfeed due to concerns about nipple confusion.
However, in light of new research refuting the link between pacifier use and nipple confusion WHO softened their policy on pacifier use:

The WHO recommends counselling on the use and risks of pacifiers, but no longer prohibits use in term infants.5“

Below are some studies rejecting the link between pacifiers and nipple confusion:

However, evidence suggests that it might not be pacifier use that causes premature cessation of breastfeeding, and that use of pacifiers might only be a sign of a maternal decision to stop breastfeeding. PMID: 23673585

There seems to be no reason to restrict the use of pacifiers in newborns, as the results of our meta-analysis suggest that they are not associated with breastfeeding duration or success rates. doi: 10.1007/s00431-022-04559-9

This meta-analysis shows that pacifier use does not decrease breastfeeding duration in full-term infants. The new evidence contradicts current WHO recom-mendations, however, which are based on less rigorous studies. PMID: 22577637

No difference between restricted and unrestricted pacifier use groups was found in the proportion of infants who were exclusively breastfed at three months of age (RR 1.01, 95% CI [0.96 to 1.07], 2 trials/1228 infants; I²=0.00%) or at four months of age www.who.int

Alternative feeding supplementation

This section exists for you to be aware of the existing options, alternative feeding methods pose their own set of challenges and risks. Alternative supplementation methods should be evaluated on a case-by case basis together with a healthcare professional or lactation consultant.

In some cases short term nutritional supplementation is medically required, particularly when an infant exhibits low initial weight, inability to latch or showing poor weight gain. Several supplementation methods exist that protect the breastfeeding relationship and do not involve a bottle or an artificial nipple.

At six months post-discharge, the overall likelihood of full breastfeeding was increased by 64% among those infants who received additional feeds via gavage tube or cup (RR 1.64, 95% CI [1.14 to 2.36], p=0.0071; I²=52%), and the effect of both interventions remained statistically significant in subgroup analyses (both p≤0.0059). e-Library of Evidence for Nutrition Actions

It was found that the preterm babies in whom spoonfeeding was used as a supportive method in addition to breast-feeding switched to full breastfeeding in a shorter time compared to the babies who were fed by bottle and their sucking success was at a better level. PMID: 26078682

These are intended as a temporary solution most often for newborns until breastfeeding can be established. It is highly recommended that a trained healthcare professional or lactation consultant demonstrate the technique first.

Resources describing alternative feeding methods:

• A Detailed Look at Alternative Feeding Methods for Supplementing Breastfed Babies: A Guide for Lactation Consultants - margaretsalty
• Alternative Methods of feeding for breastfed babies NHS-Wales
• Nipple Shield - ClevelandClinic

Baby bottles

Work in progress:

• Flowrate: https://pmc.ncbi.nlm.nih.gov/articles/PMC5033656/
• Shapes: https://pmc.ncbi.nlm.nih.gov/articles/PMC12150115/
• Reference: https://blog.lactapp.es/en/how-to-choose-a-baby-bottle/
  • https://www.nurturedfoundation.com/nurtured-foundation-blog/best-bottle

Paced bottle feeding

Unlike traditional bottle feeding which uses continuous flow, paced feeding replicates breastfeeding’s rhythm of suck–swallow–pause. While this technique is often used to prevent nipple confusion in babies who switch between breast and bottle, its advantages make it a good choice for exclusively bottle-fed babies as well.

The core goal of this technique is to reduce the flow of milk, requiring the baby to actively suck to extract it. This is a shift from traditional feeding, where gravity does the work and milk is essentially poured into the baby’s mouth.

How to

A paced bottle-feed should typically take around 10-20 minutes, similar length as a breastfeeding session. These are not hard numbers, just general reference points to queue you in whether the pace is right.

The baby should be sitting semi-upright in your lap at around 50 degrees angle. Always use your hand to support their neck and upper back.

Alternatively you can place the baby laying down and sideways on a pillow in your lap. They should be facing to the side with their backside touching your abdomen. In my experience this is more conformable both for the baby and the caregiver. The side-laying position is especially good for night feeds since it allows to eat while drowsy.

After placing the baby, touch the bottle tip to their upper lip, and wait for the baby to open the mouth and accept the bottle.

Maintain the bottle is a somewhat horizontal position. The bottle should be inclined enough so the tip is always full but not as inclined so gravity forces the milk out of the bottle. The actual angle of the bottle needs to be constantly adjusted depending on how much milk is left in the bottle.
A good litmus test for the correct angle: The tip of the teat is full, the base of the teat is not.

Bad angle examples:

In the picture to the left the angle is not steep enough, the tip is not full. The baby should ingest air together with the milk, it causes digestive discomfort.

In the picture to the right the angle is slightly too steep, the base of the teat should not be full. A steep angle can make your baby take too much milk in one gulp.

Good angle

In the picture above the angle is correct: The tip is full so no air will be ingested. Bottle is not too inclined so that gravity forces milk out of the teat.

Let the baby suck on the bottle for around 20-30 seconds, then lower the bottle to a horizontal position so the nipple tip is totally empty. This simulates the breastfeeding let-down pause.

Note: During pauses the baby might gulp air by sucking on the empty teat, this is ok. Counterintuitively they swallow less air with a fully empty teat than they would have with a partially filled teat.
If the air swallowed in such a manner becomes problem for you, you can remove the bottle all together from their mouth during breaks. This did not work for me, my daughter got very angry every time I tried removing the bottle from her mouth.

This is an excellent short video demonstration of paced bottle feeding.

Advantages of paced bottle feeding

Prevents over-feeding

You might have heard that “you can’t overfeed a breast-fed baby”. Extracting milk from a breast is an active process, when the baby stops being hungry they can just stop sucking and the meal ends. Receiving milk from a bottle with traditional bottle feeding techniques is a passive activity, gravity pulls the milk into baby’s mouth and their only option is to swallow it. By letting the baby “do the work” and extract the milk by themselves the risk of overfeeding is eliminated.

Reduces Gas and Reflux

Because the milk flow is not continuous, and we include frequent pauses for breathing, the baby avoids gulping or gasping for air. This controlled pace ensures the baby ingests significantly less air, which helps prevent digestive discomfort.

Avoids nipple confusion/flow preference
(This applies only to babies who switch between breast and bottle)

Bottle nipples require less effort the active sucking needed to trigger milk letdown. Flow preference refers to the situation where the baby gets accustomed to the faster flow and refuses to breastfeed. By incorporating regular breaks and encouraging a natural suck–swallow–pause rhythm paced feeding lowers the risk of your baby developing bottle preference .

Prevents the baby choking on milk
Especially early on, some babies have difficulty managing breathing and eating at the same time. They will breathe in while trying to swallow at the same time, which makes them choke. Reducing the flow of milk and offering constant pauses helps them manage better the suck–swallow–breathe rhythm.

Choosing baby formula brands

Work in progress

Preparing baby formula

Breastfeeding vs Formula

Every public health organization will encourage exclusive breastfeeding for at least the first 6 months of life. There is good reason for that: For one breast milk is the most nutritionally complete food a newborn can eat. In addition, breast milk allows antibodies from the mother to pass to the infant via the milk, effectively short-term boosting their immune system.

This gave us the omnipresent “Breast is best” slogan. I’m neither qualified nor I have the intention to disagree; However, it is quite common for “breast is best” to transform into “breast is the only option”. In this section I will argue that “Breast is best, but formula is also OK”.

Some important background: Starting around 1920 formula manufacturers began aggressively marketing it as a better alternative to breast milk. These marketing tactics are now widely considered as predatory, reaching levels where physicians were being paid to convince new parents to switch to formula feeding alleging false health benefits.
This led to a steady decrease in breastfeeding rates across the world, creating suboptimal health outcomes. This was especially pronounced in the underdeveloped regions where access to clean water and sanitary conditions of preparation is limited.

As a response WorldHealthOrganization and Unicef created the Baby-Friendly Hospital Initiative, which instructs health professionals on providing guidance and promoting breastfeeding. You can read more about this from WorldHealthAssociation directly or from here. Overall a positive change, but it had the unfortunate outcome where in some cases “encouragement” becomes societal pressure (E Grattan et al).

In addition to the above, there is another complicating factor:
All research on breastfeeding is observational. Instead of a designed study with randomized groups, participants self-select into breastfeeding vs non-breastfeeding groups (for obvious ethical reasons researcher’s can’t discourage breastfeeding to “see what happens”). Families with high socio-economic status are more likely to breastfeed (Martje Van Neste et. al.) but the same cohort of people have access to better medical care, not smoke, be better informed on safe sleep practices and in general have more positive health outcomes. With all these confounding factors attributing a particular benefit to breastfeeding becomes tenuous. The PROBIT and the Improved Estimates of the Benefits of Breastfeeding Using Sibling Comparisons to Reduce Selection Bias studies try to address this bias and concluded that

nonexperimental studies of breastfeeding overstate some of its other long-term benefits, even if controls are included for race, ethnicity, income, and education.

Hank Green explains much more eloquently this point in this 13 minute SciShow video.

The point I’m trying to make here: Even trustworthy sources will occasionally oversell the benefits of breastfeeding while casting formula in an exaggerated negative light. Sometimes even the scientific community over-corrects and swings in the opposite end of the spectrum.

If a mother desires and is able to breastfeed exclusive breastfeeding until 6 months is indeed the ideal option. If not formula feeding or supplementing is also a perfectly viable option. Baby formula is one of the most tightly regulated food items on the market and is the only existing alternative to breast-milk suitable for newborns. In 2026 only 52% of newborns were exclusively breastfed for the first 6 months.

[!WARNING] All of the above applies to a healthy baby that was delivered on term. Babies born preterm or with very low weight are at higher risk for Necrotizing Enterocolitis. Human milk has a demonstrated protective effect against this disease.

Preparing baby formula

Before opening the can

• Check expiration date on the bottom of the can. Past this date nutrients begin breaking down and the formula stops fulfilling baby’s nutritional needs. This is applicable even if the container remained sealed.
• Inspect the container for damage. While minor dents are ok, any damage that allows air or humidity to enter the container makes the formula inside unsafe for use. If you see any signs of rust discard the container and contents, rust is a clear indicator the formula was exposed to high level of humidity which is the ideal environment for bacteria to multiply.
• Write on the container the date when you unseal it. Powdered formula needs to be used within 30 days after unsealing the container. Writing it down on the can/box ensures you will not use expired formula by accident. See Bacteria and hygiene for context around formula expiration dates.
• Do not put the container under running water. If you want to clean the outside of the container, use a disinfectant wipe.

Preparation steps

Each formula can or box will come with detailed preparation steps printed on the package. This section fils some gaps that are often skipped in the prep instructions.

• Decide how much formula you want to prepare. Preparation instructions on the can will include a table of recommended amount per age/weight of the child These amounts are a general guidelines and not rigid rules. For example this is the table for Nestle NAN 1.

• Wash and dry hands and working surface.
• Measure and pour the water first. This guarantees the proportions of watter to powder are exact.
  • Use boiled tap water. See chapter Tap or bottled water for context.
  • The instruction on the can will indicate what temperature the water should be when adding the powder. See the Water temperature for context .
• Mix in the powder following the dosage table printed on the formula container. The proportion of water to powder volume needs to be exact. An isolated mistake of overdiluting or underdiluting a meal is unlikely to be dangerous but repeatedly feeding formula mixed in wrong proportions can have serious negative health effects ranging from digestive issues and abnormal weight gain to clinical emergencies like salt poisoning (hypernatremic dehydration) or water intoxication. Sources PMC11335633 and PMC6834868
  • Always use the scoop provided with the can/box. Never use a scoop from a different brand as scoop sizes differ across brands.
  • Avoid heaping scoops, which can make the feed too concentrated. Scrape the scoop against the built-in leveling edge of the container to remove the extra powder and leave the top perfectly flat.
• Close the baby bottle and shake for a few seconds.
• Always check the temperature of the mix before offering by pouring a few drops on your wrist.
  • Mouth burns caused by formula that is too hot are very common.
  • Do not heat formula in the microwave. Microwave heats liquids unevenly creating hot-spots in the mixture.
• Throw away any formula left in the bottle after the feed. Once formula comes in contact with baby’s saliva the bacterial growth accelerates drastically making the mix unsafe to consume later, even if stored in the refrigerator.

Storing

• Formula in powdered form can be stored up to 30 days at room temperature.
• Keep the lid tightly closed and avoid humidity entering the container.
• The formula scoop can be stored inside the container.

Also see making-up-baby-formula guide from NHS for an official resource on the topic.

Bacteria and the role of hygiene in formula preparation

This section contextualizes why preparation guidelines were created and what they are designed to protect against. With context established the reasoning behind every “step” should become self-evident.

Guidelines for the preparation and storage of powdered infant formula focus primarily on preventing contamination and limiting bacterial growth. The two main risks are Cronobacter sakazakii (Enterobacter) and Salmonella enterica contamination. PMC6874386. These bacteria occur naturally in the environment and pose little threat to a healthy adult but can be dangerous to a newborns. While all infants are vulnerable, those under two months face a heightened risk, and babies born prematurely or with weakened immune systems are in the highest risk category.

Both above-mentioned bacteria can survive in dormant form even in dry environments but start rapidly multiplying when water is introduced.

While contracting a disease from these bacteria is unlikely, proper handling is essential since these infections can be extremely serious if they do occur. According to sections 1.2.1 and 1.2.2 of the WHO report on safe formula handling and PMC6874386

In the United States of America, an incidence rate of 1 per 100 000 infants for E. sakazakii infection has been reported. (2006)

The United States of America reported a salmonellosis incidence rate of 139.4 cases per 100 000 infants in 2002.

(E. sakazakii ) It has an incidence of 2–5% in premature infants and 13% in those weighing less than 1.5 kg at birth.

Powdered infant formula can get contaminated in three ways:

• During production: Formula manufacturing is strictly regulated and plants are often inspected but PIF is not a sterile product. Although rare, contamination sometimes occur during production. When this contamination is detected the affected batch is recalled.
• From water used for mixing.
• From the environment during preparation. (dirty surfaces, unsanitized hands etc.)

By following proper preparation procedure both the risk of contamination is greatly reduced, but also ensures any potential bacteria already present in the powder is not allowed to multiply, so it can be handled by the newborn’s immune system.

Tap or bottled water

Using boiled tap water is the most common way to prepare baby formula, assuming your tap water is safe for human consumption.

Some countries add fluoride to their drinking water supply for its beneficial effect on dental health. Fluoridated tap water is considered safe for formula preparation and health authorities don’t currently advise parents against using it. If water fluoridation is one of your concerns see Annex: Fluoride in tap water for a deeper dive.

Bottled water is not recommended for formula preparation. Just like tap water it is not sterile and needs to be boiled before mixing. Additionally, bottled water can contain a high level of sodium (which can cause salt toxicity in newborns PMC4500422) and other minerals that can put strain on infant’s kidneys.

If you must use bottled water, avoid natural mineral water and opt for low mineralization water instead:
Ideally the bottled water for formula preparation has a dry residue <250 mg/L and sodium <20mg/L (non-academical sources glenaqua.es and hydrasana.com)
These numbers are not set-in-stone but should give you a frame of reference. For scale: a popular high minerality natural water in my region has a dry residue of 3052 mg/L and a sodium content of 1097 mg/L, making it clearly unsuitable for infant consumption.

Water temperature when adding the powder

Guidelines from both the NHS and WHO instruct boiling the water and mixing the powder while the water is at no less than 70 degrees Celsius.

Boil the water. Then leave the water to cool for no more than 30 minutes, so that it remains at a temperature of at least 70C. NHS

Taking care to avoid scalds, pour the appropriate amount of boiled water, which has been allowed to cool slightly, but not below 70 °C. WHO

CDC on the other hand recommends using cold tap water for most cases CDC - formula preparation and storage but boiling and mixing at 70 degrees only for high-risk groups: less than 2 months old, born prematurely or ones with weakened immune systems. CDC - extra precautions

To make things even more confusing the preparation instructions on some cans of formula instruct the caretaker to boil the water but cool it to less than 40 degrees before adding the powder. For example instructions on Nestle’s NAN 1 Infant Formula

Why these guidelines differ and what’s the right way to do it?

By boiling the water any potential bacteria contained in water is eliminated. By adding in the powder while the water is at least 70 degrees any bacteria in the powder itself is destroyed, effectively sterilizing the mixture. This way of preparing PIF is the safest and virtually removes all possibilities for getting sick from Cronobacter. See Bacteria and hygiene in PIF preparation and NEC for a more detailed explanation.

Why then the contradictory recommendation from CDC and formula manufacturers?

Some modern formulations of baby powder contain probiotics which are destroyed when the powder is mixed with hot water. If your formula brand has added probiotics or other heat-sensitive ingredients it will likely instruct you to mix the powder with cold water.

A secondary reason for the CDC recommendation of using cold water is that boiling water before every feed (once every 3 hours) is highly impractical in a household setting, often making caretakers prepare large batches at once and storing them improperly.

What I ended up doing myself:

I am against preparing formula in large batches. While it is safe to store formula at <5 Celsius for up to 24 hours, if my fridge fails to maintain the low temperature for any reason (power outage, door left open, fauly sensor, etc) any contaminants in the already mixed feed will multiply aggressively.

I boil a large amount of water, let it cool and keep in the same pot with the lid on for the next 24 hours. When preparing a feed I will mix the correct amount of powder and water in the baby bottle itself and offer it to the baby within the next few minutes.

By using room temperature water and mixing one feed at a time before serving I can ensure that in the unlikely chance that bacteria is present in the powder, it does not get a chance to multiply so it can be managed by my daughter’s immune system.

Annex: Fluoride in tap water

Fluoride is a naturally occurring mineral that is often added to drinking water supply for its beneficial effect on dental health. In very high doses this mineral becomes toxic, and often in online forums concerns are raised around using fluoridated tap water for formula preparation. The reasoning behind this concern is that formula-fed newborns will consume much more fluoride per kg of body weight than a breastfed baby or an adult.

Water fluoridation was not a particular concern in our case and we used boiled tap water for preparing infant formula, but I feel this topic deserves representation and some scrutiny as it is very often miss-represented.

The impossibility of acute fluoride poisoning from fluoridated tap water:

In the US the maximum allowed fluoride concentration in tap water is 0.7mg/L while in europe the maximum permissible concentration is at 1.3mg/L. In high concentrations fluoride is indeed toxic, the lethal dose for an adult is 64mg/kg of body weight. Babies are not adults, but extrapolating it would mean that a 3kg baby would need to consume 274 liters of water in one sitting suffer deadly fluoride poisoning (3*64/0.7).

In concentrations of 0.3 mg/kg of body weight fluoride is not life-threatening but can cause gastrointestinal discomfort. That would mean that the same 3kg baby would need to consume more than one liter of water in one sitting to experience the side effect. Reference numbers from wikipedia and US National Institute of Health. Obviously these numbers are ridiculous, which is corroborated by the reference material.

This dose would be virtually impossible to achieve from water or toothpaste containing standard levels of added fluoride.

Historically, most cases of acute fluoride toxicity have followed accidental ingestion of sodium fluoride based insecticides or rodenticides.[10] Currently, in advanced countries, most cases of fluoride exposure are due to the ingestion of dental fluoride products

Effects of long term exposure to fluoride:

Things are less clear-cut when conversation shifts towards the side effects of long term exposure to smaller doses. The scientific consensus leans towards “artificially fluoridated water is safe for formula preparation” but there is some debate for this.

One of most common effects of prolonged intake of high levels of fluoride is dental and skeletal fluorosis.

Dental fluorosis

Dental fluorosis is a cosmetic condition that alters the appearance of the tooth enamel, changing its color to a more yellow tint. The effects are cosmetic only, does not affect tooth function and is not painful CDC article. To reduce the risk of dental fluorosis EFSA (European Food Safety Authority) recommends an intake of maximum 0.05mg fluoride per kg of body weight per day.

Balancing the benefits of caries prevention against the risk of dental fluorosis, EFSA recommended an AI of 0.05 mg fluoride/kg b.w. per day from all sources for children and adults, PMC7261729

The hypothetical 3kg baby used for calculations would need to consume around 2 liters of fluoridated water at 0.7mg/liter to be at risk of dental fluorosis. Developing dental fluorosis from drinking water alone is possible but very unlikely.

Skeletal fluorosis

Skeletal is a bone disease caused by deficient mineralization of the bones making them more prone to fractures. This is a more serious condition but is reversible in some cases if fluoride intake is stopped.

Skeletal fluorosis is endemic in several countries where the potable water sources naturally contain high fluoride levels (>4 mg/L), and where water consumption is high due to hot climates (EFSA 2013). Fluoride intakes of above 6–8 mg/day may increase the risk of bone fractures PMC7261729

At fluoridation levels of 0.7 mg/L to consume 6 mg of fluoride one must drink around 8.5 liters of water daily for a significant amount of time.

Association between IQ and fluoride consumption

Some studies point out an association between diminished non-verbal intellectual abilities and water fluoridation.

Exposure to increasing levels of fluoride in tap water was associated with diminished non-verbal intellectual abilities; the effect was more pronounced among formula-fed children. PMC6913880

Others claim no correlation and re-state the safety of water fluoridation.

This population-based follow-up study has provided consistent scientific evidence that early-life exposure to fluoride was not negatively associated with cognitive neurodevelopment. The findings, in combination with the current body of knowledge, provide assurance that the currently practiced WF programs are both effective and safe for young children. PMC11843800

These meta-analyses show that fluoride exposure relevant to community water fluoridation is not associated with lower IQ scores in children. S0033350623000938

This rapid systematic review indicates that community water fluoridation at concentrations between 0.7 and 1.0 mg/L is not associated with adverse nondental health effects in the general population. However, exposures exceeding the WHO guideline of 1.5 mg/L may increase risk of health effects, particularly among children and other susceptible groups. S2161831325001851

In conclusion: At current maximum allowed levels of fluoridation 0.7mg/L in US and 1.3mg/L in EU developing negative health outcomes from consuming fluoridated water is virtually impossible. Fluoridated water is considered safe for formula preparation and health authorities don’t currently advise parents against using it.

Annex: NEC and Preterm or Low birth weight infants

Necrotizing enterocolitis is life-threatening gastrointestinal disease affecting predominantly newborn babies. The exact cause for it is unknown. It manifests as an inflammation of the intestine which allows bacteria to infiltrate the colon tissue. More about it here.

This disease typically occurs in 2-6 weeks after birth. Babies born with low weight or under 28 weeks of gestation are especially vulnerable. It affects 2-5% of premature infants according to the study Jacob G. Ginglen, Nikolai Butki.

Formula feeding has been identified as one of the primary risk factors for developing NEC. Studies like A. Lucas and T.J Cole suggest a 6-10 times decrease in incidence for breastfed babies, and 3 times less common in babies who were mixed fed. (I can’t find the original paper, sorry).

For high risk babies, breastfeeding is highly encouraged for this reason. In case breastfeeding is not feasible, some NICU units offer access to pasteurized donor milk.

If formula feeding is the only option, WHO recommends using Sterile ready-to-feed (RTF) infant formula when possible. It is pasteurized during production and has the lowest risk of being contaminated during handling by the caretaker.

Where feasible, sterile liquid infant formula should be used in care settings, especially when feeding highrisk infants. These feeds do not contain harmful bacteria. Care settings, such as neonatal intensive care units, provide care for infants at greatest risk of E. sakazakii infection, i.e. neonates and those less than two months of age. However, sterile liquid infant formula is not always available (e.g. for infants who have special dietary needs), and PIF might be used instead.

Section 2.2.1 of Safe preparation, storage and handling of powdered infant formula Guidelines

If you are in this situation, definitely have discussion with your healthcare professional and do not rely on general guidelines.