Who knew swaddling your baby could be so risky? I loved swaddling my daughters, and they seemed to calm instantly as I tucked them up in soft flannel cloth, feeling (I imagined) safe, contained and protected.

But, like so many aspects of child-rearing, one wrong move can produce a major screwup. In this case, according to new research published in the journal Archives of Disease In Childhood, improper swaddling can lead to hip dysplasia. (The key to safe swaddling, experts say, is to allow the baby's legs to bend, rather than wrapping them up with their legs tightly extended and pressed together.)

Infant swaddling has, historically, been a near-universal practice, researchers report, and in recent years it's enjoyed a popular "resurgence." Why? Because it genuinely appears to calm kids down with "its perceived palliative effect on excessive crying, colic and promoting sleep," researchers write. "Approximately 90% of infants in North America are swaddled in the first few months of life."

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WBUR and NPR's Here & Now explored the topic today, quoting the study's lead author — Nicholas Clarke, a consultant orthopaedic surgeon at the Southampton University hospital in the U.K. — on how best to swaddle a baby: