A new study out of Pediatrics

[1] has the media once again proclaiming that bedsharing is unsafe, particularly in the 0-3 month age range.  The study, which utilized data from the National Centre for Review and Prevention of Child Death Case Reporting System, examined details pertaining to over 8000 deaths in the period of 2004-2012.  Although the sheer number of deaths examined is impressive, what the data actually tells us is far less so, especially for the take the media has got on it.

First let’s start off by admitting that they did try to examine a pretty important question: What are the risk factors for death at different ages?  This is important because most parents assume the risks remain the same when in fact, this may not be the case at all, and what is a safe sleeping environment at one age may not be safe at another.  However, what they have actually answered is more akin to looking at the situations that infant deaths occur in when compared only to other infant deaths.  In this regard, the authors found that younger infants (0-3 months) who died of SIDS or suffocation were more likely to be found in the parental bed than older infants (4-12 months) and were more likely to have been placed on their side or stomach (prone position).  Older infants, on the other hand, were more likely to have other items in bed with them such as blankets, toys, stuffed animals, and more than younger infants.

What do we take from this?  Well, not much.  We have descriptive data for the environments infants are found in when they suffer SIDS or suffocation, but we have no data on how this compares to children who did not die, which is necessary to make any risk assessment.  Although the authors claim that bedsharing is riskier for younger infants, it is equally likely that more infants bedshare in the 0-3 month age group because that is the time that they are often nursing throughout the night and bedsharing means that process becomes easier and parents sleep better.  As infants start to sleep longer stretches, parents may be more likely to put their infants in a cot for those longer times.

If we look at the data, it seems a risk may not even be present.  In this dataset, 73.8% of infants aged 0-3 months were bedsharing at time of death while only 58.9% of older infants were bedsharing at time of death.  For this to be a higher risk, this has to be a higher percentage than naturally occurs in this age group as if the naturally occurring number is the same, then just by sheer chance, a similar proportion should be found (assuming no additional risk factors).  Although this research does not speak to that, one study of nearly 300 mothers asked what their sleep practices were with their 3-month-old infants found that 72% admitted to bedsharing regularly[2].  (Note that other studies have found lower rates, but it’s unclear what the rate actually is.  Many parents don’t admit to bedsharing but do practice it.  Many parents say they do not bedshare because it’s not an intentional practice yet bring their baby to bed every night for a period.  In short, we need more data that really addresses all types of bedsharing when talking to parents.)

If we use these numbers, the relative risk ratio would clearly be non-significant at 1:1.025, meaning that there would be a 2.5% increased risk for bedsharing without considering confidence intervals (and I can tell you from a lot of stats experience, that kind of increase isn’t going to result in significant differences above and beyond chance).  Notably, if the numbers were to hold for the 4-12 month age group (which I don’t know), we could actually start to argue that not bedsharing becomes a risk (but somehow I doubt the numbers are the same given the same reasons mentioned above).

The other problem with this research is that by using nationally collected data, there is virtually no information on the main risk factors that interact with bedsharing.  As reported elsewhere[3], when these risk factors (which include parental smoking, alcohol or drug use – including prescription and over-the-counter medications, soft mattress, too many blankets, prone sleeping position, non-breastfeeding, and more) are accounted for, bedsharing does not seem to indicate a higher risk for SIDS or suffocation.  Another study[4] also found that the intentionality of bedsharing is critical to the issue of risk with intentional bedsharing not resulting in any increased risk of death whereas unintentional bedsharing is associated with an increase, likely due to the unsafe nature of unplanned bedsharing.

Does this new study tell us that bedsharing is “unsafe” or “riskier” for young infants?  No.  Not even close.  All this tells us is that younger and older infants are dying in different environments when they die of SIDS or suffocation.  This should not be too surprising as the environments for older and younger infants reflect the various needs and developmental stages they are at.  As mentioned above, younger children tend to bedshare more than older ones given the ease of nursing and the ability to provide parents with more sleep.  Unfortunately, not all parents actively seek to ensure a safe bedsharing environment, perhaps because education on the matter is so scarce in the face of anti-bedsharing campaigns.

Although the authors have attempted to speak of risk factors, the data they have examined simply cannot speak to that as there was no comparison with the actual prevalence rates of these behaviours in children that did not die.  The authors attempt to paint their data as condemning of bedsharing, especially in infancy, and yet they have failed to not only accurately assess the risk of bedsharing, but have failed to capture any of the known risk factors that interact with bedsharing.

In short, this study adds nothing to question of how safe or unsafe bedsharing can be.  All it does is continue to add to the dogma that bedsharing is dangerous whilst providing zero evidence to support that view and failing to consider the wealth of data that has been accumulated on the subject.  So long as we continue to preach this dogma of unsafe bedsharing, we run the risk of setting new parents up to put their babies in unsafe sleep environments.  As always, accurate and scientific education – not fear – needs to be the cornerstone of safe infant sleep advice.

Note: A more recent study did the appropriate analyses and found that the risk of SIDS for younger infants is NOT increased by bedsharing when other factors are considered.

Safe Bedsharing

[1] Colvin JD, Collie-Ackers V, Schunn C, Moon RY.  Sleep environment risks for younger and older infants.  Pediatrics 2014; doi:10.1542/peds.2014-0401.

[2] Ateah CA, Hamelin KJ.  Maternal bedsharing practices, experiences, and awareness of risks.  Journal of Obstetric, Gynocologic, & Neonatal Nursing 2008; 37: 274-81.

[3] Blabey MH, Gessner BD.  Infant bed-sharing practices and associated risk factors among births and infant deaths in Alaska.  Public Health Reports 2009; 124: 527-34.

[4] Vennemann MM, Bajanowski T, Brinkmann B, Jorch G, Sauerland C, Mitchell EA.  Sleep environment risk factors for Sudden Infant Death Syndrome: the German Sudden Infant Death Syndrome study.  Pediatrics 2009; 123: 1162-70.