Bounty

The risk of babies suffering from cerebral palsy is increased if the child is born past its due date, researchers claim.

Although prematurity is known to be linked to the condition, not much was known about the effects of birth at over 40 weeks.

Norway's University of Bergen studied data on 1.7 million children who were born between 1967 and 2001.

The babies were delivered from 37 weeks' gestation through to 44 weeks. The study followed the health of the children until 2005 using data from different national registries in Norway.

Of all the babies born at term or afterwards, 1,938 were identified as having cerebral palsy.

Analysis showed that babies born at 40 weeks had the lowest chances of cerebral palsy, but the risk was higher if the baby came earlier or later.

At 37 weeks, the risk almost doubled, and was 30% higher at 38 weeks.

At 42 weeks' gestation, babies were 40% more likely to have cerebral palsy than those born at term and the risk was also 40% higher for those born after this time.

Of those babies whose actual gestational age was confirmed by ultrasound scans, the study could pinpoint the risk with greater accuracy, and found it to be even higher.

At 37 weeks, babies had an almost four times higher risk of cerebral palsy as those born at 40 weeks and the risk was more than double for those delivered at 42 weeks.

While 40 weeks is regarded as full-term, doctors generally consider there are low risks to the baby if it is born between 37 and 41 weeks. Birth before 37 weeks is considered premature.

The study was published in the Journal of the American Medical Association.

Copyright Press Association 2010