Babies born past term associated with increased risk of cerebral palsy

August 31, 2010, JAMA and Archives Journals

While preterm birth is a known risk factor for cerebral palsy, an examination of data for infants born at term or later finds that compared with delivery at 40 weeks, birth at 37 or 38 weeks or at 42 weeks or later was associated with an increased risk of cerebral palsy, according to a study in the September 1 issue of JAMA.

Cerebral palsy (CP), the most common cause of physical disability in childhood, with limitations that persist throughout life, is characterized by nonprogressive disorders of movement and . "One of the strongest predictors of CP is preterm birth, with the risk of CP increasing steadily with earlier delivery. Although risk is lower among term births, about three-fourths of all infants with CP are born after 36 weeks. Within this range of term births, there are few data on the possible association of CP with ," the authors write.

Dag Moster, M.D., Ph.D., of the University of Bergen, Norway, and colleagues examined the relation of CP risk with gestational age among term and postterm births using the Medical Birth Registry of Norway, which identified 1,682,441 children born in the years 1967-2001 with a gestational age of 37 through 44 weeks and no congenital anomalies. The group was followed up through 2005 by linkage to other national registries.

Of the group of term and postterm children, 1,938 were identified as having . The researchers found that infants born at 40 weeks had the lowest risk of CP, with a prevalence of 0.99/1,000 births. Risk for CP was higher with earlier or later delivery, with a prevalence at 37 weeks of 1.91/1,000 (90 percent increased risk), a prevalence at 38 weeks of 1.25/1,000 (30 percent higher risk), a prevalence at 42 weeks of 1.36/1,000 (40 percent increased risk), and a prevalence after 42 weeks of 1.44/1,000 (40 percent higher risk).

The authors add that these associations were stronger in a subset with gestational age based on ultrasound measurements, with a gestational age of 37 weeks associated with a 3.7 times higher risk of CP; and 42 weeks, a 2.4 times higher risk. Adjustment for infant sex, maternal age, and various socioeconomic measures had little effect.

"Clinicians typically regard term births (37-41 weeks) as low risk, with the possibility of increased risk with postterm delivery. This standard definition of term does not correspond well with the period of lowest risk for CP in this study or with the weeks when most infants are born. Weeks 37 and 38 seem more to resemble weeks 42 and 43, both in CP risk and in the general likelihood of delivery, leaving 39 to 41 weeks as the optimum time for delivery. If the time of delivery affects CP risk, then intervention at 40 weeks might reduce CP risk, while elective delivery at 37 or 38 weeks might increase it. If infants prone to CP are disrupted in their delivery times, the prevalence of CP would be unchanged regardless of time of delivery," the researchers write.

"Until the biological mechanisms for these patterns of risk in term and postterm births are better understood, it would be hasty to assume that interventions on gestational age at delivery could reduce the occurrence of CP."

More information: JAMA. 2010;304[9]:976-982.

Related Stories

Recommended for you

Sleep better, lose weight?

January 17, 2018
(HealthDay)—Sleeplessness could cost you when it's time to stand on your bathroom scale, a new British study suggests.

Who uses phone apps to track sleep habits? Mostly the healthy and wealthy in US

January 16, 2018
The profile of most Americans who use popular mobile phone apps that track sleep habits is that they are relatively affluent, claim to eat well, and say they are in good health, even if some of them tend to smoke.

Improvements in mortality rates are slowed by rise in obesity in the United States

January 15, 2018
With countless medical advances and efforts to curb smoking, one might expect that life expectancy in the United States would improve. Yet according to recent studies, there's been a reduction in the rate of improvement in ...

Teens likely to crave junk food after watching TV ads

January 15, 2018
Teenagers who watch more than three hours of commercial TV a day are more likely to eat hundreds of extra junk food snacks, according to a report by Cancer Research UK.

Can muesli help against arthritis?

January 15, 2018
It is well known that healthy eating increases a general sense of wellbeing. Researchers at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have now discovered that a fibre-rich diet can have a positive influence ...

Your dishwasher is not as sterile as you think

January 13, 2018
(HealthDay)—Your dishwasher may get those plates spotless, but it is also probably teeming with bacteria and fungus, a new study suggests.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.