Swaddling and Sudden Infant Death Syndrome

A brief article in the Science Times section of the New York Times this morning was enough to strike terror into the hearts of young parents: it associated swaddling of babies with SIDS. The article reported a risk of SIDS increased by about one third for babies who were swaddled, with the greatest risk for those sleeping in the prone position.

For readers who haven’t come across this, swaddling is a traditional infant care technique that involves wrapping a baby, fairly tightly, from feet to neck. The head is free and sometimes the arms are too. Some Native Americans used to do this by binding the baby to a cradleboard. As I understand it, the Russian tradition was to use long strips of fabric and to keep the baby swaddled much of the time until a year of age. (These babies were frequently unwrapped to be fed and cleaned, of course.) According to some observers, swaddled babies were sometimes so thoroughly bound that they could be picked up by the feet without bending their bodies. The purpose of swaddling was described as keeping the babies warm, making them easy to carry, and calming them. In developed countries today, swaddling is infrequent except for very young infants who may be tightly wrapped in blankets as a soothing measure. Older babies are usually put into “sleep sacks” or “sleeper” suits to keep them warm while avoiding the loose bedding associated with suffocation during sleep.

So, what about this article that looks at swaddling as a cause of increased SIDS rates? The article, by Anna Pease and colleagues, is titled “Swaddling and the risk of Sudden Infant Death Syndrome: A meta-analysis.” It appears in Pediatrics, May 2016 (pediatrics.aappublications.org/comtemt/early/2016/05/05/peds.2015-3275).

Pease and her colleagues did a meta-analysis by examining data from four studies of SIDS cases, with each case compared to a control infant who did not die. The studies used had appeared over a period of 20 years and used cases from parts of England, from Tasmania, and from Chicago. About 35% of babies were swaddled in Tasmania in the 1980s when that study took place, while about 9% were swaddled in Chicago in the 1990s, about 10% in an English study ten years ago, and about 6% in a more recent English study. Across all studies, about 17% of the babies were swaddled for the sleep that ended with their deaths, and about 10% of the surviving, control babies were swaddled. However, only in the English studies was the difference between swaddled and unswaddled babies’ deaths a statistically significant one, and only in the more recent one did this statistical significance remain after adjustment for other possible causes of SIDS. Babies found dead in the prone position were more likely to have been swaddled, and older babies who were swaddled were more likely to die than younger swaddled babies, whatever their sleep position.

Pease and her colleagues did a careful job of stating the limitations on conclusions that could be drawn from their study, and especially noted that none of the four studies they worked with gave a careful definition of swaddling. They did not advise against swaddling young babies, but did note that there should be an upper age limit of about 4-6 months on swaddling.

For me, this study raises questions about other factors that could both encourage parents to swaddle older babies and increase the chances of SIDS. Why, for example, did any of the parents in these studies continue to swaddle an older baby? The reasons could have had to do with the baby’s own characteristics; when a baby still sleeps very poorly and is easily distressed at age 4-6 months, parents may try to soothe him or her by swaddling or other techniques that were recommended to them much earlier, but there may be developmental problems related to the poor sleeping that are the actual causes of SIDS. Or, the reasons could emerge from characteristics of the parents; parents who abuse drugs or alcohol or suffer from physical or mental illnesses may choose to continue to swaddle because of difficulty in thinking about their babies’ developmental status and needs, or because they are especially disturbed by infant awakening and crying, all situations that are associated with less adequate physical and medical care for infants. Finally, use of swaddling with older infants may be associated with living conditions; parents might choose to swaddle older babies to keep them from rolling off a bed or sofa where they were put to sleep in the absence of a crib, or because of demands of other household members that they try to keep the baby quiet, all of these suggesting the poverty and overcrowding that can compromise infant health and make SIDS more likely.

Factors that make SIDS more or less likely are complex, and it is difficult to pull out single factors that by themselves cause or prevent SIDS.   In addition, making changes—for example, in sleeping position—may pose some developmental risks as well as possibly being associated with a decreased SIDS rate. Babies who use pacifiers/dummies have been reported to have lower SIDS rates, but it is not clear whether rhythmic sucking has a protective factor or whether the parents who provide a pacifier have other characteristics that make SIDS less likely.

Is there a take-home message here? Am I saying swaddle or don’t swaddle, sleep prone or sleep supine? No, simply that we all need to take a deep breath and think carefully about SIDS information as it emerges. It will take a long time to understand this complicated and terrifying phenomenon, and it is not likely that there will be a single action that will save our babies. All parents can do is their best, and it’s an awful truth that sometimes that’s not good enough.