By Will Dunham
Babies born four to six weeks prematurely have more than triple the risk of developing cerebral palsy than full-term babies, US researchers said.
The study focused on the specific serious neurological problems associated with late preterm births - babies born between 34 and 36 weeks of pregnancy. Increasing numbers of these babies are being born in the United States.
Researchers led by Joann Petrini, an epidemiologist with the March of Dimes advocacy group, tracked 141 321 babies born between 2000 and 2004 in the United States.
The late preterm babies were about 3,4 times as likely to develop cerebral palsy as full-term babies. They also were about 25 percent more likely to develop learning, speech and other developmental delays and mental retardation as full-term babies, according to the study.
Cerebral palsy refers to a group of disorders that affect a child's ability to coordinate body movements. Symptoms range from mild to severe and may include lack of muscle coordination, stiff muscles and exaggerated reflexes, walking problems, drooling and tremors.
It is incurable and frequently requires long-term care. Other neurological problems including mental retardation or seizures may appear in children who have cerebral palsy.
About 800 000 children and adults in the United States have cerebral palsy, according to the March of Dimes.
"We know that very preterm babies have higher rates of cerebral palsy from existing research, but this paper shows that even the late preterm babies are three times as likely to be diagnosed with cerebral palsy as full-term babies," Petrini said in a telephone interview.
In this study, very preterm babies - those born after 30 to 33 weeks of pregnancy - were eight times as likely to develop cerebral palsy as full-term babies.
The researchers said previous studies showed that late preterm babies also had higher rates of respiratory distress, jaundice, seizures, feeding problems and other problems.
In the United States, growing numbers of babies are being born prematurely. About 70 percent of all preterm births fall into this late preterm birth category.
Petrini cited several factors behind the rise in late preterm births. These include more older women and women with obesity, diabetes and high blood pressure having babies, more babies being delivered by Caesarean section, and more being conceived after fertility treatments.