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people have been wrapping their babies like burritos since before there were burritos. my husband described the skillful nurses where i gave birth as "swaddling ninjas," and by my estimation he had at least his brown belt by the time we left.

but people have also been worrying about their babies dying in their sleep for millennia. today, about 3,500 sleep-related infant deaths occur each year, including 1,500 from sudden infant death syndrome. it's only in recent years that researchers have explored whether the two are connected: could the age-old practice of swaddling increase the risk of sids?

headlines about a study in the journal pediatrics would suggest as much, but the research didn't actually find increased risk when parents follow other safe sleep guidelines.

"this study was really looking at old data and trying to put together really apples and oranges," says harvey karp, an assistant professor of pediatrics at the university of southern california school of medicine. he says media coverage missed "the forest for the trees and emphasize[d] this scary outcome which the study wasn't even reporting."

the study is a meta-analysis, research that combines results of previously published studies and analyzes the data together. the most recent of the studies included in this meta-analysis was published in 2009, and the findings reaffirm much of what doctors already knew.

"we only found four studies and they were quite different, making it difficult to pool the results," senior author peter blair, a professor in social and community medicine at the university of bristol in the united kingdom, said in an email. "this we have emphasized as strongly as any of the findings, but does not seem to get as much media coverage. given the weak evidence, we do not conclude that swaddling is a risk factor for sids but rather that more evidence is needed."

the four studies compared a total of 760 infants who died from sids with 1,759 infants who didn't. the researchers in each study noted the percentage of infants who were swaddled in each group, along with data on their ages and the positions the infants were placed down in and found in.

"more thought needs to go into at what age swaddling provides reduced benefit and potentially more risk as the infant grows," blair said.

the combined analysis reiterated what scientists concluded in the 1990s: the biggest risk factor for sids is placing babies on their stomach to sleep. swaddling just increases those odds further — 13 times more than placing them on their backs. side sleeping also triples the odds of sids, partly because babies can too easily end up on their stomach.

"i would be shocked if there were any pediatricians out there who didn't already consider that to be a greater risk factor than prone sleeping when not swaddled," says clay jones, a neonatal hospitalist at newton wellesley hospital in newton, mass.

despite these unsurprising conclusions, media outlets seized upon the finding that swaddled babies placed on their back also have an increased risk of sids and that swaddled babies over 6 months old are twice as likely to die from sids. but those findings are "unconvincing," says jones, concurring with the study authors. he found the conclusion about babies older than 6 months odd since sids risk is highest between 2 and 4 months.

"with so few cases occurring past 6 months, this could be a statistical fluke," jones said. "perhaps these were babies being placed in a very tight wrap in order to keep them swaddled, but i'm not convinced it is a real phenomenon."

it may also be that older babies can roll and break out of swaddles, increasing the risk of smothering or suffocation, the authors noted.

still, swaddling has clear benefits, jones says. the danger of media coverage suggesting otherwise can make strung out, exhausted parents feel they've lost a crucial tool for calming their babies and keeping them asleep.

"the issue really is about reducing crying and increasing sleep," says karp, who included swaddling as one of the five strategies he recommends combining to calm crying babies in his book and dvd the happiest baby on the block. (disclosure: i enthusiastically recommend his evidence-based methods to all new parents because they saved my sanity with two kids.) "those are the two biggest pain points that new parents have."

discouraging a key strategy for addressing crying and poor sleep has been implicated as a risk factor for abusive head trauma, for example, when parents shake or otherwise injure a child out of sleep-deprived desperation.