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The most common cause of severe physical disability among children is cerebral palsy. Each year, about 10,000 infants in the U.S. are born with it. The condition can make even simple movements, sitting up or moving an arm, a struggle. There's no cure, but increasingly, doctors are focused on early therapy and interventions.
NPR's Allison Aubrey reports on who's at risk of cerebral palsy and what can be done to help.
ALLISON AUBREY: When Kim Falk was pregnant with twin boys eight years ago, her doctors had given her a heads-up that her babies would likely be born a little early. She just never anticipated how early. They arrived 11 weeks premature, which put them at risk of many complications, including cerebral palsy.
Ms. FALK(ph): We did know the risk of, you know, me having preterm labor, but nobody had really educated us on the fact that this would happen.
AUBREY: At first, both boys seemed relatively healthy for preemies, but then Kim learned that one of her twins, Ethan, had suffered bleeding in the brain. And by six months, she noticed that Ethan wasn't moving nearly as much as his brother.
Ms. FALK: When Andrew was starting to try to crawl and sit up, I mean, Ethan was not able to do those things.
AUBREY: Ethan was diagnosed with cerebral palsy when he was about 18 months old. And experts say, given how prematurely he was born, his risks were much higher - at least 14 times greater than a full-term baby.
Dr. JANET SOUL (Neonatal Neurologist, Children's Hospital Boston): That's true. Every week that a baby is born earlier increases their risk of cerebral palsy.
AUBREY: Janet Soul is a neonatal neurologist at Children's Hospital in Boston. She says the link between premature birth and cerebral palsy has been known for decades. But the lingering question is why?
In the case of severe preemies, it seems clear that the condition develops as a result of the early birth - given how underdeveloped the brain and central nervous systems are. But a new study published this week in the Journal of the American Medical Association suggests that even babies born just a few weeks early are at higher risk of cerebral palsy too.
Dr. SOUL: This new study does show that children who are born just two or three weeks earlier than term age have a higher risk of cerebral palsy.
AUBREY: This is a brand-new finding, but Soul says she's not really surprised. It fits with a spate of new studies showing that babies born just a few weeks shy of the normal 40-week gestation period are more prone to a range of complications, including feeding and respiratory problems.
Dr. SOUL: Because I think, in general, biology usually gets it right. And so we know that 40 weeks is the usual time for delivery. And so it probably shouldn't be that surprising that the farther you deviate from that, the more trouble you're likely to have.
AUBREY: Experts say these findings may give pause to obstetricians and moms-to-be who might try to schedule or induce a birth a little early just for convenience's sake. But when babies arrive early on their own, which is often the case with twins and multiples and do develop cerebral palsy, there's increasing evidence that starting physical therapy early helps.
Mom Kim Falk enrolled her son Ethan in a physical therapy study at the University of Nebraska two years ago.
Ms. FALK: We have certainly seen improvement with his head control and being able to keep his head up.
AUBREY: Some children with cerebral palsy have trouble moving just one side or one limb. For Ethan, whose case is more severe, physical therapists have found that repeated exercises to build trunk and core muscles beginning at about 12 months of age helps build the strength needed to sit and eat independently.
Allison Aubrey, NPR News.