For more than a decade, tens of thousands of parents have been flipping babies on their backs to combat Sudden Infant Death Syndrome. Their efforts have been largely successful, say experts, but as is almost always the case in the medical world, every solution comes with side effects.

FLAT-HEAD SYNDROME, aka plagiocephaly, has increased fivefold according to some studies.

"We started paying attention to it after the first couple of 'sleep on the back' years," said Dr. Mitch Adams, a Provo pediatrician.

But a fear of SIDS is not the only reason for the thinning number of Charlie Browns in the population.

The first reason is a good one: Three decades ago premature babies could be saved only after spending at least 34 weeks in the womb. That week number is down into the 20s, said Stephen Minton, chief of neonatology at Utah Valley Regional Medical Center in Provo. But all those preemies with their under-developed skulls are especially susceptible to plagiocephaly.

Zachary Magleby came 17 weeks early and was on his back for the first four months of his life. Now a year old, Zachary's head "matches up with the wall," said his mother Christina Magleby.

Magleby and her son have worked with a physical therapist, mostly training him to get "tummy time."

"He wasn't a big fan of that," Christina said. "Even after he came home he'd been sleeping like that for so long that was just the way he slept."

They waited to see if the problem would correct itself, as it often does. But in Zachery's case, it's probably going to take a little more. He recently got fitted for a helmet that allows for back sleep while giving space for his skull to round out.

The helmets, which can cost nearly $2,000 because they're customized to a specific child, have become more prevalent as insurance companies start to pick up the tab, said Adams, the pediatrician.

There is also a higher demand because of plagiocephaly's other cause: Parents are not picking up their infants when the infants are awake. Instead, they often turn to miracles of modern technology like the Graco Metrolite Laura Ashley Travel System. For a few hundred dollars, you get a stroller and car seat combo. And because the car seat snaps in and out of the stroller and the vehicle, often the baby simply stays put after reaching a destination.

"It's changing our habits of how we take care of our kids. We're going to have to be more actively involved with them," Adams said.

While plagiocephaly's effects are mostly cosmetic, often there are related developmental problems. If children are spending too much time on their backs, milestones such as sitting and rolling over can be delayed, Adams said. And if the little tyke resists your efforts for tummy time?

"You need to force the issue," Adams says.

There is also a serious medical condition related to flat-head syndrome.

Craniosynostosis is a birth defect in which the sutures between the skull's six plates fuse prematurely. That stops skull expansion and causes severe pressure as the brain continues to grow. It is a serious condition that needs treatment immediately, says Minton, the UVRMC chief of neonatology.

CAUSES OF FLAT HEAD SYNDROME

Back sleeping - Excellent for fighting SIDS, but prolonged back sleep can deform the head. To combat such problems, make sure the baby gets plenty of "tummy time" when awake.

Extended time in a carrier - In a go-go world, having the tyke strapped in can be convenient, but too much time can lead to misshapen skulls. Combat the problem by bending over, unclicking the restraints and picking the child up.

More premature babies being saved - Underdeveloped skulls are prone to being misshapen. Three decades ago premature babies could be saved at 34 weeks in the womb. Today it's in the 20s.