About That Scary Swaddling Study

A new meta-analysis seems to link infant swaddling with a higher risk of SIDS. But there’s more to the data than that.

Damir Sagolj / Reuters

One of the more frightening risks faced by new parents—other than, you know, everything—is the prospect of SIDS, or Sudden Infant Death Syndrome, which results in some 2,000 unexplained deaths every year in the United States. So it’s understandable that a new meta-analysis that links swaddling to a higher risk of SIDS is getting a flurry of attention.

The study, published this month in the journal Pediatrics, analyzes a total of 760 global SIDS cases compared with 1,759 control babies. Its findings, which come from analyzing four studies of SIDS deaths in the 1980s and 1990s, reinforce the guidance that babies should be put to sleep on their backs. But they also raise a question about the safety of swaddling infants—even those placed on their backs when they’re put to sleep. (SIDS rates have declined sharply in recent years, a reversal health officials attribute to the success of the “back to sleep” campaign that instructs caregivers to put infants to sleep on their backs.)

The researchers identified a “small but significant risk” associated with infants swaddled and put to sleep on their backs—a risk that’s evident in the discrepancy between the percentage of babies who died after having been swaddled and put to sleep on their tummies (under 2 percent) and the percentage of swaddled babies who were ultimately found in that position (7.9 percent).

In other words, it seems some of the infants who died of SIDS and who had been swaddled and put to sleep on their backs—the position that’s recommended—were found on their stomachs anyway. This may have to do with age. The SIDS risk increased for swaddled babies as they got older—perhaps because once babies were able to roll, even the swaddled ones could end up on their stomachs. (Some doctors recommend swaddling with one or both arms out as babies get older—so that if they roll over, they have enough range of motion to keep their faces off the mattress or otherwise move about.)

The larger question is whether parents should interpret the findings of this meta-analysis as a reason not to swaddle. That’s less clear.

After all, among the babies who died of SIDS, all but the youngest cohort weren’t swaddled. Meaning: Even though the babies who died of SIDS were more likely to have been swaddled than the control group of surviving babies, most SIDS deaths were among babies who weren’t swaddled to begin with.

Nearly one-third of the babies who died of SIDS were put to sleep unswaddled and on their backs; and about 30 percent of the babies who died were found in that position. (In contrast, under 6 percent of the SIDS deaths occurred in babies who were swaddled and put to sleep on their backs.)

The study’s authors say their findings reinforce the importance of putting babies to sleep on their backs, especially when they’re swaddled. They also suggest that doctors talk to parents about phasing out swaddling as babies get older.

These are good suggestions, but the idea that swaddling and SIDS are substantially linked is misleading.

The biggest limitation to this research may be the definition of swaddling itself. The authors of the study acknowledge one of the “several” limitations to their meta-analysis is the fact that none of the studies they reviewed clearly outlined what constitutes a swaddle. And besides that, as anyone who has tried to swaddle a baby can confirm, good swaddling takes practice. Many parents, for fear of too tightly wrapping their babies, end up swaddling too loosely, which is itself a suffocation hazard. (Some daycare centers in the United States don’t allow swaddling for this reason.)

The biggest takeaway here, then, may be that if you’re going to swaddle a baby, you should make sure to do it properly. And if you don’t think you can do that, given the importance of keeping a baby’s crib free of loose blankets and bedding, perhaps it’s best to skip the swaddle altogether.