TORONTO -- Almost half of Canadian infants develop flat areas on the back of their heads by the age of two months, likely the result of sleeping face-up to prevent sudden infant death syndrome (SIDS), a study suggests.
The study by Calgary researchers is believed to be the first in Canada to look at the incidence of what's known as plagiocephaly, a flattening of the back of a baby's skull.
"What we found out was that when we studied infants that were seven to 12 weeks of age coming into two-month immunization clinics in Calgary, almost half of them had some sort of flat spot on their head," said Aliyah Mawji of the school of nursing at Mount Royal University in Calgary.
"That was pretty surprising. I didn't anticipate that it would be that high."
Plagiocephaly occurs because the bony plates of a baby's skull are soft and have not yet fused together. This flattening at the back of the head -- typically on one side or the other, based on how the infant lies -- can cause facial and other changes.
"If they've got a flat spot on one side, what that likely means is that they've got the forehead protrusion on the same side and they also have a bit of ear shifting forward on the same side," said Mawji.
While the distortions are cosmetic and rarely cause a medical problem, left untreated they can become permanent and affect the child later in life.
"I would assume that if you've got a child that looks a little bit different than some of the other kids in their class, they might be at risk for bullying," she said. "Because you've got the chin that points in the other direction, you've got some shifting of the nose and the ears and the eyes and the forehead.
"They're going to look a little bit different. So we do need to be careful about that."
The study, published in Monday's issue of the journal Pediatrics, involved 440 infants aged seven to 12 weeks who were assessed for plagiocephaly during well-baby visits at four Calgary community health centres in 2010.
Researchers found 205 -- or 46.6 per cent -- had some head-flattening. Almost two-thirds were affected on the right side of the back of the skull and almost 80 per cent had a mild form of the condition.
Only a few of the infants had flattening on both sides of the back of the head, a condition called brachycephaly.
Mawji said newborns often have some flat spots on their skulls as a result of their position in the womb or from pressure during vaginal birth, but this usually resolves at about six weeks of age.
Flat spots that persist are usually caused by how the child lies during sleep, activities during waking hours and feedings.
"So if the baby is constantly placed in the same position... either the same feeding position or the same sleeping position or being left in car seats or bouncy swings, we see more of what we call the positional plagiocephaly," Mawji said.
-- The Canadian Press