Researchers have long known that babies born many weeks or months before their due dates are at an elevated risk of cerebral palsy, a lifelong condition that can cause mild to severe physical disability.
Now, new research published in the Journal of the American Medical Association finds that infants who arrive just a little early — at 37 or 38 weeks' gestation — are at risk too.
"What we're observing is that babies born a little before 40 weeks or a little afterwards have higher risk too," says study co-author Allen Wilcox of the National Institute of Environmental Health Sciences.
The study found that a baby delivered at 38 weeks — two weeks shy of the mother's due date of 40 weeks — is twice as likely as a full-term baby to develop cerebral palsy. The risk is even greater for babies born more prematurely — up to 14 times higher for babies born at 33 weeks' gestation. The study is based on data collected in a Norwegian birth registry that includes more than 1.6 million births between 1967 and 2001, and it fits with a flurry of recent studies suggesting that babies born a little early are more prone to a range of complications including feeding and respiratory problems.
Each year about 10,000 babies in the U.S. develop cerebral palsy in the months after their birth. In some cases, children may struggle to move one limb or one side of their bodies. In more severe cases, children come to rely on wheelchairs to move around.
There is no cure for the disability, but increasingly there is a focus on early intervention to prevent the development of cerebral palsy in infants. Researchers, for instance, are studying the effectiveness of using magnesium sulfate at the time of delivery to protect the brain of preemies. There are also experiments using head cooling — lowering the infant's body temperature a couple of degrees for a period of several days.
"There are some possibilities of things you could do to prevent cerebral palsy by intervention," says Nigel Paneth, a professor of epidemiology and pediatrics at Michigan State University.
Early Physical Therapy
Evidence shows that physical therapy is helpful in ameliorating some physical disabilities in children with cerebral palsy, which is normally recognized by parents and caregivers when the children are between 6 and 8 months old.
Kim Falks first noticed the difference in her twin boys when one son, Andrew, started to sit up and crawl. "Ethan was not able to do those things" Falks says.
After Ethan was diagnosed with cerebral palsy at 18 months of age, she started therapy for him and enrolled him in a physical therapy study at the University of Nebraska Medical Center. The study was designed to determine how best to help kids with cerebral palsy learn to sit up independently.
"We've certainly seen improvement with his head control and with him being able to keep his head up," says Falk. Therapists have found that exercises aimed at building trunk and core muscles can help build the strength children need to sit and eat independently.
And doing the exercises more than once a week is important too — the study compared the effectiveness of one session per week with that of several sessions.
"The children who had therapy two times a week seemed to make further progress," says Regina Harbourne, a professor of physical therapy at the University of Nebraska Medical Center's Munroe-Meyer Institute. "A greater percentage of the kids were crawling and had more variety of movements."