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Mattress firmness test

Disclaimers

Warning

While this test is scientifically sound and designed by specialists it has its limitations. No test performed at home can come close to the rigour of industrial testing done in a laboratory with dedicated equipment. If at all possible, I strongly urge you to buy certified baby sleep products, which makes this test unnecessary.

That said I felt compelled to include this as not everybody has access to the same consumer protections most of us take for granted.

At 18 months old, when we moved our daughter to a floor bed with an adult mattress, at that age she was not in the risk group anymore, and we already had experience using two other baby mattresses. We could tell by “feel” if a mattress is firm enough. Hence, I never did this test myself, nor I can speak about its accuracy.

Methodology

The steps are outlined here.

This methodology was submitted in “Australian and New Zealand Journal of Public Health” in 2012 by Ronald L. Somers. The original article can be found here.

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.