written by Tara Haelle

I have written before about how the infant sleep recommendations of the AAP and the US public health community in general are unrealistic and even potentially dangerous in their effects, regardless of their intentions. A new study in Pediatrics explores the contribution of different risk factors to sleep-related infant deaths, offering findings which are certainly valuable in understanding how risk varies as a child ages. However, I see many of the same flaws, primarily missing data, that prevent the possibility of truly evidence-based recommendations.

So once again, I feel it’s necessary to review – in addition to what the study found – all the things the study neglected to consider. Again, the flaws are not so much a result of the analysis but of the data not available to the investigators. In analyzing this study, I had a number of questions that the lead author, Jeffrey Colvin, MD, JD, of the Department of Pediatrics at Children’s Mercy Hospital in Kansas City, MO, answered via email. One of the questions he generously calculated for me was particularly enlightening – the association of bedsharing as a risk factor across causes of death. (Spoiler alert: bedsharing was much less likely among SIDS cases than among suffocation/asphyxiation and undetermined causes.)

But before I launch into all of that, it’s important to explain WHY this issue, and why pointing out flaws in these studies, is so important.

New parents receive a barrage of advice from every direction, solicited and unsolicited: their parents, other relatives, friends, virtual friends in online social networks, random strangers online and in real life – and of course all the experts: pediatricians and other professionals both in person and through media reports. Inevitably, this advice is conflicting, but hopefully most parents give a bit more weight to what their doctors say. After all, a doctor’s advice is supposed to be based on the evidence.

But what if the evidence base is horribly incomplete on an issue, a life or death issue, in fact? Vaccines are a life or death issue, but the research consensus is overwhelming, and studies have explored every possible avenue to examine the safety and effectiveness of official recommendations. The evidence base on bedsharing/cosleeping, SIDS and other infant sleep deaths, however, includes a large body of evidence yet remains woefully inadequate.

In addition, the research findings that have been published lack context. Just as there are risks – albeit tiny – to vaccination, there are risks to NOT bedsharing for many parents. Yet, I have yet to see a single study discuss this, or even consider the possibility that, at the population level, not bedsharing could carry any risk. Every single action and inaction carries risk, as do the opposite actions/inactions. It’s all a matter of balancing those risks, and parents need all the information they can get about risk to make informed decisions.

This most recent study does offer some information on risk factors for infant sleep deaths and these are no doubt valuable to other researchers and those shaping public policy, but because of significant gaps in the data, a lack of a control group and a lack of overall context, the findings cannot help parents or pediatricians much. (I will use “bedsharing” from here on because it’s the term used in the study and it eliminates confusion since “cosleeping” can mean sharing a room but not a bed.)

The study’s goal was to assess the extent to which established risk factors for sleep-related infant deaths vary by a baby’s age. The researchers analyzed data on 8,207 deaths in children less than a year old, all occurring during sleep but not resulting from a medical condition or firearm. The data came from cases voluntarily reported between 2004 and 2012 in 24 states to the National Center for the Review and Prevention of Child Deaths Case Reporting System.

They divided the children into 5,677 younger (0-3 months old) and 2,530 older (4 months to 364 days old) infants. Although an autopsy was performed in 98% of the cases, the largest category of cause of death was “unknown/undetermined,” with 38% of the children. SIDS was listed for 35% and accidental suffocation/strangulation was listed for 27%.

On the one hand, it’s helpful to have these causes separated since these categories used to be collapsed into one. As the authors note, SIDS has declined since 2000 while accidental suffocation/asphyxiation has increased, but it’s likely this shift is due to the fact that suffocation/asphyxiation cases are often no longer categorized as SIDS. That said, this data is self-reported from across the country, and different regions have different criteria for classifying SIDS vs. suffocation vs. strangulation vs. unknown/undetermined, a limitation noted by the authors in their discussion.

The Findings

I’ll provide an abbreviated list of the findings to refer back to as I discuss the flaws in the study (including the definitions used for these categories):

69% of the infants were “bed-sharing” (74% younger, 59% older)

33% of the infants had one or more “dangerous objects” in the sleep environment (33% younger, 39% older)

39% were placed to back on their sleep, but 27% were found on their backs

22% were placed on their stomachs to sleep, but 38% were found on their stomachs

13% were placed on their sides, and 12% were found on their sides

15% changed from their backs to their stomachs during sleep (14% younger, 18% older)

49% were found in “an adult bed or person” (52% younger, 44% older)

28% were found in a crib, bassinet or playpen (25% younger, 34% older)

17% were found in an “other” place (17% younger, 16% older)

Only 3.3% were found in a car seat/stroller/infant chair, and 3% were “unknown”

Let’s start with the risk factors studied: “sleeping in something other than a crib, bed-sharing, soft bedding, bumper pads or other items, and sleeping in the prone position.” A significant factor missing from this list is whether either parent smoked. Secondhand smoke is considered a risk factor for infant sleep deaths but is not mentioned anywhere in the study. Neither is the use of any other tobacco products, alcohol, medications (such as legal opiates, sleeping pills, etc.) or illegal drugs.

When I asked Dr. Colvin about this, he said that the database actually does contain data on prenatal smoking, postnatal smoking, tobacco exposure, illicit drug use during pregnancy, and abuse of over-the-counter drugs during pregnancy. He and his colleagues realized the value of that data in hindsight, he said, but are working on another study using the same data set and will be including that information in the new study. He did not say that the database included information on alcohol use or on non-abusive use of OTC drugs (such as properly prescribed and taken painkillers).

I also asked whether breastfeeding information was included in the database, an important consideration for two reasons: breastfeeding is significantly protective against SIDS, and rates of breastfeeding tend to be higher with mothers who bedshare. Unfortunately, however, the database does not contain any info on breastfeeding, a regrettable data gap the researchers will have to consider in their limitations in the next study as well.

Next, it’s important to note that the study did not include a comparison group of infants who did not die in their sleep. The study was designed only to compare circumstances among the deaths themselves. While I recognize the objective of such a study, it severely limits the utility of information.

If 69% of the infants were bed-sharing, how does that compare to the general population? If 69% of all infants share a bed, then it’s not surprising at all that 69% of all the deaths involved bed-sharing — that would be a one-to-one ratio. At least one study from last year puts the number reporting bedsharing at 13.5%, but another small-ish Canadian study in 2008 found that 72% of mothers reported occasional or regular bedsharing. That’s a huge variation, and I would expect it is due at least in part to US parents’ reticence to admit they bedshare, given the strict recommendations against it. (I will admit to having lied to my pediatrician because I wasn’t in the mood for a lecture.) Similarly, the percentages of infants with objects in their beds or sleeping prone do not mean much without information on what percentage of the general infant population sleep prone or with objects in their environments.

Definitions Used in the Study

Next, the definition of bed-sharing and of the sleeping surfaces themselves are problematic. Bedsharing was defined as the baby “sleeping on the same surface with a person or animal.” The study doesn’t note how many incidents involved animals, but Dr. Colvin told me it was 23 of the 5,681 incidents. (I neglected to ask how many involved sleeping with another child, such as a sibling.) Twenty-three is not enough to make much impact on the findings, but it still seems problematic to collapse these into one category because of what I will get to later – intentionality to bedshare.

Under sleeping surfaces, an “adult bed” included the following: “adult bed, waterbed, adult mattress, bunk bed, child’s bed, sofa bed and air mattress.” I wanted to confirm that couches were not included in this category, and Dr. Colvin confirmed that the “other” category included “couch, chair, floor, beanbag, bunkbed, cot, cushions, pallet/futon and hammock.” (I assume “bunkbed” is an error here since it’s listed under adult bed in the study.)

It’s good that couches were not included along with beds since that has been a weakness of past studies, but it’s concerning that waterbeds and air mattresses were lumped in with standard adult beds given the greater potential for the former to contribute to suffocation. (Again, there likely were not many waterbeds or air mattresses – another question I should have asked and did not – but there is a huge difference between bedsharing on a water bed versus a firm adult mattress, and conflating the data from these is unhelpful.)

It’s worth noting that 69% of the infants were bedsharing but only 49% were found on an “adult bed,” so almost a third of the bedsharers were sleeping on a different surface (most likely an “other” given the percentages reported above). Since most non-adult-bed surfaces would be particularly unsafe for bedsharing (and therefore – hopefully – not likely to be planned), it’s already easy to see that the 69% figure is problematic in offering a sense of how risky planned bedsharing would be.

Next, “dangerous objects” included “blanket, pillow, bumper pads, stuffed toys, clothing, cords and bag,” but “blanket” included “blanket, afghan, quilt, comforter, sleeping bag, bedding and swaddling.” While this is a reasonable “dangerous objects” list, the inclusion of swaddling, a very common practice encouraged by hospitals, greatly complicates how the data is interpreted.

When I asked Dr. Colvin about this, he said they did not have data coded to say the infant was swaddled. Rather, all they had to work with was data coded to say a “blanket was in the sleep environment,” which could be swaddled or could not, depending on who did the coding and whether they considered that to be an additional object (or just part of clothing). Of course, becoming unswaddled during sleep could certainly present asphyxiation risks, so it’s not that it’s unwise to consider this factor at all, but better differentiation in the data and more precise coding would help in teasing out actual risk factors.

In fact, 65% of the infant deaths (including 67% of younger infants) had no objects at all in the sleeping environment. I find it very hard to believe that the GREATEST possible number of infants 3 months and younger who were swaddled was 33%, so there was likely significant variation in how swaddling was (or was not) coded in data reporting.

The authors address this surprising finding, noting that it’s “interesting that younger infants were less likely to be found with objects in the sleep environment.” They say it’s unclear whether this is inaccurate coding – pillows, blankets, etc. weren’t mentioned – or whether it means that bedsharing “even without extraneous objects is hazardous for these youngest infants.”

In fact, they even directly address whether guidelines to reduce the risk of death while bedsharing actually reduce any risk: “It has been assumed by some that bed-sharing can be made safe if measures such as eliminating soft bedding from the adult bed are followed, but our findings raise questions about the validity of this assumption.” I would propose that their findings raise questions about the validity of data collection, and that question is no less valid than their presumption that bedsharing without pillows or blankets is still dangerous.

The Big Missing Link

And this brings us, once again, to the biggest piece of missing information: whether the parents planned intentionally to bedshare. I asked the author about whether this information was available, and his answer reiterated the possibility discussed in the study: “No, we didn’t have direct data about intention to bed share or intention to make bed sharing safe. However, we have a little insight into the question about making bedsharing safe. For instance, although the younger group (< 4 months old) was bedsharing in approximately 75% of the deaths, they had objects in the sleep area in less than 50% of the deaths. We don’t know if that is due to incomplete coding by the state child death review teams (because presumably you would have blankets and pillows in the bed) or if some of these deaths occurred in a situation where all objects (except for the bedsharing adult) were removed, but a death still occurred. It gave our research team many doubts about the possibility of ‘safe bedsharing.'”

The problem is that there is a huge difference between someone who shares a bed with a baby out of desperation late at night, unplanned, or who accidentally falls asleep while breastfeeding or trying to calm a baby, and a family which intentionally plans to cosleep and takes precautions to reduce the risk of suffocation. Without knowing who was or was not even trying to “safely bedshare,” how can it even be assessed whether safe bedsharing is possible?

One area where this is particularly important is in breastfeeding – again a protective factor against SIDS but not available in the data. A mother who intentionally plans to cosleep in the same bed with her child is more likely to arrange the child during breastfeeding so that if she falls asleep during breastfeeding, the child is in a safer position. But a mom who does NOT plan to cosleep in the same bed yet falls asleep while breastfeeding in bed or elsewhere is less likely to arrange the baby to prevent suffocation or smothering. I don’t think anyone would argue that accidentally falling asleep while breastfeeding puts a child at greater risk than intentionally planning for the possibility of falling asleep while breastfeeding (or planning to fall asleep, for that matter).

I can speak from experience: I have nearly *accidentally* fallen asleep while breastfeeding in the middle of the night on several occasions. During those accidental times – including times I did fully fall asleep – the baby was sitting on a boppy either in bed with me or in a chair. Those were dangerous positions. I finally had to accept that I could fall asleep while breastfeeding. When I did that, I could PLAN for the possibility of falling asleep and arrange the baby to be less likely to be smothered or suffocated. But the only way I could plan for that was to accept that I would likely end up bedsharing. If I were a new, less experienced mom trying desperately to avoid bedsharing because of the horror stories told by the AAP and the public health community, I would be less likely to plan for that possibility… but no less likely to fall asleep by accident while nursing.

And this is where I find the guidelines so rigid that they can actually lead to tragedy. If a person is trying to follow the guidelines, yet their child repeatedly wakes up in the night and won’t stay asleep in a crib, then they may bedshare out of desperation but without the information about ways to reduce risks in that sleeping environment. Or, worse, they may simply fall asleep by accident wherever they are with the baby due to pure exhaustion. Any new parent knows that it’s possible to fall asleep ANYWHERE in those early months, even standing up.

With my first son, I cannot tell you how many times in those first few weeks I nearly fell asleep – or did briefly nod off (and it doesn’t take long for a child to suffocate) on a chair, on the couch, on the floor, or in my bed while trying to rock him asleep for the 17th time that night because he would wake up every time we set him down and I had been up all night with him. I was exhausted, and each of those situations was far more dangerous than when I finally accepted that I would have to sleep with him beside me and planned accordingly. By setting parents up to fail by insisting that bedsharing is ALWAYS off-limits, pediatricians and public health advocates are setting babies up to die when exhausted parents accidentally fall asleep.

Further, we don’t know whether the children typically shared a bed or typically did not. Could some of these infants have been bedsharing because they were sick that night? Could their illness have contributed to their death, or could their illness have made it more likely that their parents would sleep with them but without knowing how to make the environment safer?

Without knowing whether there was smoking, alcohol use or drug use, whether the moms were breastfeeding, whether the children were ill, whether the parents were planning to bedshare, and whether they were taking any precautions to reduce the risk of suffocation or asphyxiation, we cannot have a complete picture of what factors truly did contribute to these infants deaths. That 69% does not mean much when not all bedsharing is equal, and continuing to assume it is simply hinders our ability to know what really increases a child’s risk of suffocation or asphyxiation.

How Do We Assess Risks?

If all of these factors were taken into account, and we had a valid comparison control group, and it turned out that bedsharing resulted in a higher risk of suffocation/asphyxiation than a child sleeping in a crib, that would not surprise me at all. And in fact, this is a good time to mention what Dr. Colvin calculated when I asked whether the association of bedsharing was uniform across causes of death. He sent me the following: bedsharing occurred among 57.9% of SIDS deaths, 77.8% of suffocation/asphyxiation deaths, and 73.6% of unknown/undetermined causes of deaths.

These calculations, though not reported in the study, are exactly what I would expect given that there is some evidence from James McKenna’s work that bedsharing may actually be protective against SIDS. That does not change the fact, however, that suffocation/asphyxiation is more likely with bedsharing than with a child in a crib. But we need to better understand how high those risks are when a person *plans* to share a bed. (In fact, the previous study I analyzed found no increased risk of SIDS – keep in mind “SIDS” included suffocation/asphyxiation deaths in that study – among bedsharing, breastfed infants over 3 months old whose parents did not smoke, whose mother did not take two or more units of alcohol or drugs, who did not cosleep on a sofa.)

I suspect that bedsharing – even after ALL the missing factors I’ve listed here are taken into account – is slightly riskier than placing a child in a crib to sleep even when a parent does plan ahead and take all the precautions to make the sleep environment safer. But I would expect both the absolute risk and the relative risk to be far, far lower than what the AAP and the public health community leads parents to believe. Further, there are also risks to sleep deprivation – and some of those are life or death. This study notes that SIDS occurs at a rate of 54 deaths per 100,000 live births, and accidental suffocation occurs at a rate of 28 deaths per 100,000 live births. That’s a 0.054% rate for SIDS and a 0.028% rate for suffocation.

Meanwhile the risk of getting into a fatal car accident is far higher. It’s impossible to compare the risk of infants’ SIDS/suffocation/sleep-related deaths and the risk of infants’ death in car accidents from drowsy driving directly. But here are some sobering stats: According to the CDC, “In the United States during 2011, more than 650 children ages 12 years and younger died as occupants in motor vehicle crashes, and more than 148,000 were injured.” Further, according to the Department of Transportation, 2.6% of all fatal crashes each year resulted from drowsy driving. There are about 33,000 fatal crashes a year in the US, so that’s more than 800 deaths a year from drowsy driving. That could be a mom or dad or child in a car driven by an exhausted parent.

We’ve also seen the utterly heartbreaking string of deaths of children forgotten in cars in the heat this summer, as we do every summer. Fatigue and exhaustion are major risk factors for a parent accidentally leaving their child in the car. Sleep deprivation and general exhaustion are not just inconveniences. They are very real dangers for parents and infants. Many parents choose to cosleep while bedsharing because it allows them to get the sleep they need. (My first son, for example, would not sleep alone in a crib. At all. Every time he was set down, he woke up within 10-15 minutes… all. night. long. Fortunately, my second son will sleep without being beside me.)

Therefore, a parent may accept a potentially slightly higher risk that her child could suffocate/asphyxiate during sleep – something that occurs to only 28 children out of every 100,000 – to ensure that everyone in the family gets sufficient sleep and the parent is well-rested enough to safely drive and function in general the next day. Yet a parent is denied all the information needed to make that risk calculation if we continue to have studies that do not accurately assess the risks of bedsharing. Of all the studies to date, not a single one has considered all the confounders (smoking, drug use, alcohol use, blankets and pillows, etc.), as well as breastfeeding, intention to share a bed, preparations for bedsharing, and preparations for the possibility of accidentally falling asleep. Without that data, we will never know what the increased risk of *intentional, planned* bedsharing, with precautions in place to reduce risk of death (it’s not possible to eliminate risk of death, regardless of where a baby sleeps), really is.

Shaming and scaring parents is not productive and can actually increase risks. While that may not be the intention of “safe sleeping” campaigns that discourage all bedsharing no matter what, that is the effect. And effects generally matter more than intentions.

I will repeat the analogy I’ve given before: if telling teenagers not to have sex does not prevent teen pregnancy, then telling exhausted and desperate parents not to sleep with their infants is not going to prevent bedsharing. The way to prevent teen pregnancy is to encourage abstinence while also teaching contraception and handing out condoms. The way to reduce suffocation deaths among babies is to encourage parents not to share a bed while also teaching them how to reduce the risk of asphyxiation if they choose to sleep with their child.