The resurgence of swaddling as a traditional technique to wrap babies tightly in blankets has been linked to the risk of babies developing hip problems. While swaddling may soothe babies, it also increases their chances of acquiring hip dysplasia.

According to Dr Nicholas Clarke, professor and consultant orthopedic surgeon at UK's University of Southampton, the problem with swaddling lies in the babies' legs which are positioned straight in blankets.

Mr Clarke said that in order for babies' hips to develop properly, their legs should be kept flexed and separated during the first six months of life. He said when swaddling is practiced, the rigid position of babies' legs can promote hip dysplasia.

Pediatric orthopedics chief Dr Anthony Scaduto of the Orthopedic Institute for Children at the University of California, said doctors have long suspected that swaddling increases the risk of hip problems since it prevents normal hip development.

In the early months of life, the hips of babies are still malleable, according to Mr Scaduto. For babies to develop normal hips, they need to be able to move their legs. This will help drive the ball of the femur deeper into the socket as the hip joints begin to move towards a more permanent state.

Mr Scaduto said if the pressure of the ball is not there, the socket will become flatter and "plate-like." When this happens, babies will develop hip dysplasia. Mr Scaduto said he has observed an increasing number of patients suspected to have hip dysplasia due to swaddling.

Meanwhile, Mr Clarke has reviewed previous studies on swaddling infants can cause babies to rouse from sleep less and experience long slumbers. He said parents are turning to the traditional technique of swaddling because of the common perception that it helps babies sleep and calm colic babies. Although swaddling helps babies sleep, it does not help colic babies, according to Mr Clarke.

Mr Clarke has observed other risk factors for hip dysplasia like family history and breech delivery. However, environmental factors like swaddling cannot be ignored by parents.