Timing of Birth Linked to Cerebral Palsy

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There may be one more reason for expectant moms to think twice before scheduling an elective Cesarean delivery to minimize the time they are pregnant. Researchers report that early or late delivery can increase the chances that a newborn develops cerebral palsy.

Cerebral palsy (CP) is a movement disorder that doctors believe originates from an injury to the brain during fetal development or early childhood. The scientists found that babies born at 37 weeks were 90% more likely to have cerebral palsy than babies born at 40 weeks, and that the relative risk was 40% higher among infants born later, after 42 weeks gestation. The overall risk of cerebral palsy among all births, they say, is still small.

While previous studies have found that babies born prior to 39-40 weeks have a higher chance of developing cerebral palsy, it’s not clear what contributes to the condition. Are early or late births triggering the brain changes that cause CP? Study author Dr. Dag Moster, of University Bergen, notes that the neonatal brain is more vulnerable to injury the further away delivery occurs from the ideal 40 weeks gestation. Or are congenital changes caused by cerebral palsy prompting these infants to birth before or after 40 weeks? The current study appears to support the latter explanation, since CP babies also tend to have lower birth weight and smaller head circumference compared to those without the condition.

That would suggest, says Moster, that simply intervening to change delivery times to occur as close to 40 weeks as possible may not affect the incidence of CP. But understanding all of the factors that may contribute to CP, including the timing of birth, could reveal the underlying biological causes of the condition. “Until these biological mechanisms are better understood,” says Moster, “it would be hasty to recommend intervention on delivery time based on this study.”