Along with breastfeeding and bathing a newborn, one of the crucial skills new parents master is the art of the swaddle.
But while wrapping baby up like a burrito in a thin blanket is known to help many babies relax and sleep better, North American parents need to be reminded that swaddling incorrectly may seriously damage a baby's developing hips. (For the correct way to swaddle an infant, click here.)
In a newsletter distributed to members of the American Academy of Pediatrics, pediatricians are being urged to watch for signs of hip dysplasia and dislocation and to warn parents not to extend their baby's frog-like legs straight. They should allow for room in the swaddle – or sleep sack – for baby to bend at the hips.
"There's a temptation to stretch [the legs]out and that needs to be resisted. They need to be able to straighten themselves out naturally and gradually," says Charles Price, a pediatric orthopedist at the Winnie and Arnold Palmer Hospital for Children in Orlando, Fla., and one of the authors of the memo.
"However, that message may not have been clearly understood by parents who swaddle their children, or by nurses who instruct parents at time of discharge following birth," he wrote in the memo.
Hip dysplasia affects about 1 per cent of North American newborns, according to recent figures.
The health concern is twofold. As more parents choose to swaddle, more babies with hip dysplasia or dislocation may have to undergo treatment – which ranges from wearing a harness or brace to undergoing surgery. These conditions can get worse with age and are linked to early adult arthritis and hip-replacement surgery.
Undetected hip dysplasia is the most common cause of hip arthritis in young women, says Dr. Price, who is also the director of the International Hip Dysplasia Institute.
A growing body of research – including research on Native American "cradle board" practices and traditional Turkish swaddling methods – shows that damaging swaddling practices carry a bigger risk of hip dysplasia (at least 20 per cent) than other well-known risk factors, such as being in the breech position or a family history.
And it's the one that parents can avoid. "You can swaddle babies wrong and get away with it, but we know that it increases the risk."