credits: Baby Sleeping Bags

Baby Sleeping

We don’t know what causes Sudden Infant Death Syndrome (SIDS). It is a diagnosis of exclusion; it includes all of the deaths for which no other cause of death can be identified. But researchers keep trying to figure out how we can prevent it.

A recent study takes another look at infant sleep position in SIDS. This isn’t a rehash of “back to sleep.” Instead, it’s a look at the role of an infant’s head being covered in SIDS. Why? Roughly a quarter of SIDS victims are found dead with their head covered by bedding. So, a team of researchers led by Dr. Edwin A. Mitchell of New Zealand’s University of Auckland decided to dig into the issue further. They wanted to identify risk factors for being found with the head covered in such cases and to determine whether having the covered head was part of the cause of SIDS.

Researchers looked at two case-control studies. The first, in New Zealand, was conducted from November 1987 to October 1990 and collected data on 393 SIDS cases; the other, in Germany, was conducted from November 1998 to October 2001 and collected data on 333 SIDS cases. The New Zealand study predated the “Back to Sleep” campaign in that country, while the German study occurred after the “Back to Sleep” campaign there.

Although the study questions were asked in different languages, both covered several common variables, including pillow use, blanket use, smoking in pregnancy, birth weight, time found dead, season, position when placed to sleep, position when found, if the infant were sweaty when found, bedsharing, and pacifier use, among others.

Researchers found that infants who were found with their heads covered tended to be older than those whose heads were not covered, probably do to their greater motor development. Older infants would be more able to wiggle under the blankets or kick the covers over themselves. However, their position when placed to sleep was not associated with head covering. Their position when found was not associated with it either.

Those who were found with their heads covered were also more likely to be sweaty. Researchers theorize that this could be due to rebreathing exhaled gases, which could cause hypoxia or hypercapnea. Another possible cause is thermal stress caused by overheating.

Duvet use was associated with head covering in the German study, although not in the New Zealand study. This difference could be due to the different materials used in these countries (German duvets tend to be heavier). Importantly, tucking in the bedding firmly did not protect against later head covering.

What’s a parent to do?
The researchers conclude that head covering is causally related to SIDS, so as parents we need to do all we can to prevent head covering from happening. Mitchell and colleagues call for “evidence on how best to achieve this,” but parents of infants today will need to make decisions now—not wait for evidence to be agreed upon, tested, analyzed, and eventually published! Here are a few common sense suggestions:

• Remember “Feet to Foot.” The United Kingdom Department of Health has popularized this phrase in its SIDS prevention pamphlet, urging parents to place their infant’s feet at the foot on the mattress so that the infant cannot slide down and cause the head be covered by the bedding. Although neither the New Zealand or German studies noted infants’ position in the bed, so we can’t form any direct conclusions about this, it seems like logical advice. However, this might not be enough—remember the study’s finding about head covering occurring even when the bedding was initially firmly tucked in?

• Keep it simple: avoid bedding. Although it can be hard to resist the darling cribsets sold at baby goods stores, you may want to avoid them—and save your peace of mind. If you use just a fitted sheet to cover the crib mattress and dress your baby in a warm sleeper, you won’t have to use (and worry about) covers in the crib.

• Use “wearable blankets.” Another option for keeping keep your baby warm in cool temperatures is the wearable blanket or sleep sack. From Halo’s Sleep Sack (available in sizes up to 2T-3T) and Sozo’s Nap Sak to Cloud B’s Lullabag and more, these pouches zip up or snap around the infant’s shoulders to stay in place during sleep. These sacks were not used by parents during the New Zealand and German studies, so this analysis did not provide any data about them. However, a 1998 study from the Netherlands did explicitly recommend sacks.