Although experts stress that the small risk should in no way prevent parents from making sure infants sleep on their backs, doctors increasingly are noting the problem and finding ways to address it.
The latest technique: a helmet custom-designed to correct shape problems in the skull.
One such helmet, already used for hundreds of children with birth defects and other conditions, recently was approved by the Food and Drug Administration for wider production and distribution by prescription. Designed by experts at the University of Michigan and Danmar Products Inc., the helmet offers a customized fit and accommodates a baby's growing head size.
Helmets are useful only during the earliest stages of life, when a baby's skull is still soft enough to be brought back into shape, says Ammanath Peethambaran, an orthotist at the University of Michigan's Orthotics and Prosthetics Center.
"If the child doesn't use the helmet by about a year of age, the correction is not very significant because the skull cannot be shaped at that point," Peethambaran says.
Most helmets need to be worn most of the time -- as much as 23 hours a day -- for about three to six months.
Although that may seem extreme to some, Dr. John Persing, chief of plastic surgery at the Yale University Medical Center, says the length of time softens the need to apply pressure.
"The idea is to put very gentle pressure on the skull," Persing says. "You don't want to put severe pressure. So, in order for it to be effective, it has to be worn as often as the child will tolerate."
Without the helmet, or before receiving one, an infant tends to roll to the flattened side more often than not, he explains.
"There will be a flattening on one side and a prominence on another side, so the flattened side is the side that's easier for the child to turn to," Persing says. "So they perpetuate the flattening by virtue of the fact that it is flat to begin with."
But, he adds, parents can play a large role in preventing that.
"The [babies] still lie flat on their back -- that's still very important in preventing SIDS [sudden infant death syndrome] cases," he says. "But, you turn the head to the right side on day one and to the left side on day two, etc. If you do that, particularly in the early stages of life, the pressures will be equalized, and you probably won't wind up having this flattened skull."
And what if children with flattened heads do not receive treatment to mold their skulls back into shape?
"It may not cause brain damage, but it certainly can single out a child for unwanted problems later on that could be due to physical distortions in the face as well as the skull," Persing says. "That's because, when you have flattening in the back of the skull, it often has facial effects not only in the cheekbones but in the jaw."
"If there's enough distortion, kids can pick up on that and, particularly around 5 to 6 years of age, it can be a real problem for children in terms of being accepted within their intended peer group, in how they socialize and even how they do in school," he adds.
What To Do
To read more about sleep positions for babies, visit the University of Michigan Web site.
And for information on the shape of your baby's head, go Neurosurgery Today.