Ever since the advice came out for babies to sleep on their backs to prevent sudden infant death syndrome, there have been more infants who have developed flat spots on their heads.
The condition was once thought to be only cosmetic, but research shows otherwise.
A helmet is the standard therapy for reshaping a baby's flattened skull. The condition is called plagiocephaly or flat head syndrome. Since the early 1990s, the number of cases has skyrocketed.
An earlier study by Seattle Children's showed that these infants and toddlers tend to lag behind their peers developmentally. And now, when researchers retested those same children at age three, they still haven't caught up.
"Motor skills like walking and fine motor skills like picking really small things and language skills and cognitive or problem-solving skills,” said Dr. Brent Collett, lead author of the study.
Dr. Collett says putting babies to sleep on their backs may be one reason for the increase in cases.
But he says that's still the safest position for sleep. What parents should do is to increase tummy time during waking hours and limit how long babies spend confined in car seats and other devices that restrict movement.
"It's gotten to be very handy, especially if the baby falls asleep and then your transport them somewhere else and they're still sleeping in this little container, but overall that might contribute to plagiocephaly and we don't think that's likely to be the best for development,” said Dr. Collett.
Flattening usually occurs on the right side of the head, Children with more severe cases do not necessarily have worse outcomes. If parents have concerns, they should check with their pediatrician about further assessment and monitoring.
The children in this study will be reassessed when they reach school age to see if problems persist.
One way to prevent flat spots is to rotate your baby's head slightly to the opposite side each time you put him or her down to sleep.