Cerebral palsy risk with term and postterm deliveries

January 01, 0001

Cerebral palsy risk with term and postterm deliveries

Preterm birth is a long established risk factor for cerebral palsy (CP). However, there is relatively little data on the risk of cerebral palsy in with term and post-term delivery. These Norwegian and US researches examined whether timing of birth within the term and postterm periods affected risk of CP. They performed a population-based follow-up study utilizing the Medical Birth Registry of Norway yielding 1,682,441 singleton births with a gestational age of 37 through 44. The cohort was followed up through 2005 by linkage to other national registries.

The researchers found: "Of the cohort of term and postterm children, 1938 were registered with CP in the National Insurance Scheme. Infants born at 40 weeks had the lowest risk of CP, with a prevalence of 0.99/1000. Risk for CP was higher with earlier or later delivery, with a prevalence at 37 weeks of 1.91/1000 and a relative risk (RR) of 1.9, a prevalence at 38 weeks of 1.25/1000 and an RR of 1.3, a prevalence at 42 weeks of 1.36/1000 and an RR of 1.4, and a prevalence after 42 weeks of 1.44 and an RR of 1.4. These associations were even stronger in a subset with gestational age based on ultrasound measurements: at 37 weeks the prevalence was 1.17/1000 and the relative risk was 3.7. At 42 weeks the prevalence was 0.85/1000 and the relative risk was 2.4. Adjustment for infant sex, maternal age, and various socioeconomic measures had little effect."

The researchers concluded: "Compared with delivery at 40 weeks' gestation, delivery at 37 or 38 weeks or at 42 weeks or later was associated with an increased risk of CP."

This study finds an increased risk of cerebral palsy with early term and post-term deliveries vis-à-vis delivery at 40 weeks.

For the full abstract, click here.

JAMA 304(9):976-982, 1 September 2010 © 2010 American Medical Association
Cerebral Palsy Among Term and Postterm Births. Dag Moster, Allen J. Wilcox, Stein Emil Vollset, Trond Markestad, Rolv Terje Lie.

Category: N. Neurological, W. Pregnancy, Family Planning. Keywords: cerebral palsy, gestational age, early term, postterm, delivery, population based cohort study, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 1 October 2010

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.

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