Did They Really Uncover the Cause of SIDS? Not Quite.

About a month ago, a study was published by Harrington et al(1) that got the whole internet excited – news articles everywhere were saying that we have found the cause of SIDS!(2) But did we really? Not quite.

Sudden infant death syndrome (SIDS) can be intimidating to discuss: the cause(s) have eluded scientists for decades. SIDS is the reason we have the Safe Sleep guidelines(3) to protect out little ones, but even though safe sleep has helped reduce deaths in the U.S. there still have been cases of infant deaths who were in safe sleep environments, so when this study was released, it makes perfect sense that people became excited.

But I’m the type of person who doesn’t believe much without reading the original studies myself. There’s nothing like seeing the peer-reviewed data and analyzing it for yourself, so I did just that, and I’m sharing with you what I’ve found!

Disclaimer: Keep in mind this is a blog, not a peer-reviewed literature review. Although I’m reviewing an original study, this review itself is not peer-reviewed and you should read the study for yourself if you want to confirm my statements. Also, I am including a critique of the study but it is not going to be inclusive of every data point or even every aspect of the study. Just some highlights!

Harrington et al(1) studied the association of butyrylcholinesterase (BChE) activity with SIDS. BChE is an enzyme in the autonomic nervous system. They measured the activity of this enzyme in dried blood samples of Australian children found in 3 different databases. They found that the BChE activity was decreased in the dried blood samples of the children who suffered from unexplained deaths prior to age 2 years.(1)

One of the study’s strengths was blinding. Specimens were de-identified from names and diagnoses and the diagnoses were not revealed until necessary for the statistical analysis. They ethically collected the samples by obtaining informed consent prior to collection and de-identification. They also disclosed no conflicts of interest and the funder(s) had no role in the study besides funding.(1) Thus, there seems to be minimal bias in this study.

Now here’s the critical part of this analysis. There were 655 control specimens in this study but only 67 specimens were associated with infant deaths. Furthermore, only 26 of those were actually from SIDS. This is a very small sample size for a study.

The researchers found a statistically significant correlation between SIDS deaths and decreased BChE activity. That finding included an adequate odds ratio but the confidence interval was broad.

Harrington et al(1) made an excellent, novel effort in this study to uncover a biomarker as a cause of SIDS. This study does not reveal a/the cause of SIDS, but it absolutely opens doors for future research.

Some key points for you to understand:

  1. These findings should NOT make you throw safe sleep guidelines out the window.
  2. These findings should NOT make you panic and think that it’s all intrinsic and there’s no way to prevent SIDS.

Why? Because even if this is found to be a cause or a contributing factor for susceptibility to SIDS, that doesn’t mean it’s the only cause, and it also doesn’t mean that safe sleep practices won’t still help to prevent SIDS.

Let’s look at it from another perspective: There are genes that contribute to lung cancer, for example. But just because genes were identified as being associated with lung cancer that does NOT mean that a)smoking no longer is seen as a contributing cause of lung cancer or b)someone with the genetic variant/mutation will get lung cancer no matter what they do.

So while we shouldn’t be changing any of our guidelines based on this data or breathe a sigh of relief for our babies just yet, we can still feel excitement over the prospect of getting one step closer to the answers we need.

Take care!


  1. Harrington CT, Hafid NA, Waters KA. Butyrylcholinesterase is a potential biomarker for sudden infant death syndrome. Lancet. May 2022;80:104041. doi:10.1016/j.ebiom.2022.104041
  2. New study may have identified cause of SIDS, or sudden infant death syndrome. ABC7 Chicago. May 13, 2022. Accessed June 5, 2022. https://abc7chicago.com/sids-cause-sudden-infant-death-syndrome-breakthrough-babies/11845007
  3. American Academy of Pediatrics. SIDS and other sleep-related infant deaths: evidence base for 2016 updated recommendations for a safe infant sleeping environment. Pediatrics. November 2016;138(5): e20162940. doi:10.1542/peds.2016-2940

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