MONDAY, July 8 (HealthDay News) -- Putting babies on their backs to sleep has sharply cut the rate of Sudden Infant Death Syndrome (SIDS), but it has also left nearly half of infants with a flattened heads, a new Canadian study estimates.
Researchers found that 47 percent of 440 2-month-olds having routine check-ups had what doctors call positional plagiocephaly -- where the back or one side of the head has a flat spot. It develops when infants spend a lot of time with the head resting in the same position against a flat surface.
Flat spots are a cosmetic issue -- not a medical problem -- experts stressed, and parents should keep putting their infants on their backs to sleep.
"It still is very important to put infants to sleep on their backs to prevent SIDS," said study author Aliyah Mawji, an assistant professor in the School of Nursing at Mount Royal University in Calgary, Alberta.
But parents can do things to prevent or alleviate the flat spot, she said -- like making sure infants have "tummy time" when they are awake and under someone's watchful eye.
The study, published online July 8 and in the August issue of Pediatrics, gives a better estimate of the incidence of flat head than past research has, according to Mawji.
That's because the babies were assessed for flat spots during routine check-ups at four community health centers across Calgary. Past studies included babies at just a single center, Mawji said, and their estimates of the rate of flat head ranged hugely -- from 3 percent to 61 percent.
Still, Mawji said it's not clear whether the rate in her study would reflect what's going on everywhere. The United States, for example, is generally more diverse than Calgary, so the rate could be different there -- and could vary across different parts of the nation.
Young infants are susceptible to flat spots because the bones of the skull are not fused together -- so that the head can get through the birth canal and the skull can accommodate a rapidly growing brain later.
In recent years, doctors have been seeing more and more cases of flat spots, which is thought to be related to the Back to Sleep campaign. For the past 20 years, experts have been advising parents to put infants on their backs to sleep, on a flat crib surface, to reduce the risk of SIDS.
The campaign (now called Safe to Sleep) seems to have worked. In the United States, it's credited with a 50 percent drop in SIDS, according to the U.S. National Institutes of Health.
So keep putting your baby on her back to sleep, said Dr. Roya Samuels, a pediatrician at Cohen Children's Medical Center in New Hyde Park, New York.
"Positional plagiocephaly is really a cosmetic issue," Samuels said. "There's no evidence that it affects the brain."
Still, she added, "parents can get concerned." To help reshape a flat spot, Samuels said she tells parents to lay their baby on her back with the head facing right, on Mondays, Wednesdays and Fridays. On the other days, face the head to the left.
If your baby has a flat spot on one side of the head, Samuels said you can also place mobiles or other interesting visuals to the opposite side of the crib. That will encourage your baby to turn her head to the non-flattened side.
When babies are awake, limiting the amount of time their heads are against a flat surface -- as in a swing or "bouncy" seat -- is also a good idea, according to Mawji. "Parents should also place their infant on their stomachs when awake and supervised," she said. "Tummy time helps promote neck strength, arm strength and shoulder girdle strength, which will help the infant reach developmental milestones."
Most of the babies in the current study had mild flat spots, and simple measures are enough to address that. Some infants, though, develop more severe flattening, causing the face to appear misshapen.
In those cases, some doctors prescribe a corrective helmet that can help redirect the growth of the baby's head.
Samuels said the most important thing is for parents to make routine well-child visits, so their baby's overall health and development -- including changes in head shape and size -- can be monitored.
While plagiocephaly is cosmetic, Samuels noted that there is another, far rarer condition that causes a misshapen head, called craniosynostosis. In that disorder, the skull bones fuse prematurely, which can harm normal brain development. It usually requires surgery.
Fortunately, positional plagiocephaly is usually the culprit behind infants' flat spots, Samuels said.
Plus, she pointed out, few people actually have perfectly symmetrical heads. "Underneath our hair, most of us have lumps and bumps," she said.
Boston Children's Hospital has more on plagiocephaly.