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JAMA. 2010 Sep 1;304(9):976-82. doi: 10.1001/jama.2010.1271.

Cerebral palsy among term and postterm births.

Author information

1
Department of Public Health and Primary Health Care, University of Bergen, PO Box 7804, N-5020 Bergen, Norway. Dag.Moster@smis.uib.no

Abstract

CONTEXT:

Although preterm delivery is a well-established risk factor for cerebral palsy (CP), preterm deliveries contribute only a minority of affected infants. There is little information on the relation of CP risk to gestational age in the term range, where most CP occurs.

OBJECTIVE:

To determine whether timing of birth in the term and postterm period is associated with risk of CP.

DESIGN, SETTING, AND PARTICIPANTS:

Population-based follow-up study using the Medical Birth Registry of Norway to identify 1,682,441 singleton children born in the years 1967-2001 with a gestational age of 37 through 44 weeks and no congenital anomalies. The cohort was followed up through 2005 by linkage to other national registries.

MAIN OUTCOME MEASURES:

Absolute and relative risk of CP for children surviving to at least 4 years of age.

RESULTS:

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 (95% confidence interval [CI], 0.90-1.08). Risk for CP was higher with earlier or later delivery, with a prevalence at 37 weeks of 1.91/1000 (95% CI, 1.58-2.25) and a relative risk (RR) of 1.9 (95% CI, 1.6-2.4), a prevalence at 38 weeks of 1.25/1000 (95% CI, 1.07-1.42) and an RR of 1.3 (95% CI, 1.1-1.6), a prevalence at 42 weeks of 1.36/1000 (95% CI, 1.19-1.53) and an RR of 1.4 (95% CI, 1.2-1.6), and a prevalence after 42 weeks of 1.44 (95% CI, 1.15-1.72) and an RR of 1.4 (95% CI, 1.1-1.8). These associations were even stronger in a subset with gestational age based on ultrasound measurements: at 37 weeks the prevalence was 1.17/1000 (95% CI, 0.30-2.04) and the relative risk was 3.7 (95% CI, 1.5-9.1). At 42 weeks the prevalence was 0.85/1000 (95% CI, 0.33-1.38) and the relative risk was 2.4 (95% CI, 1.1-5.3). Adjustment for infant sex, maternal age, and various socioeconomic measures had little effect.

CONCLUSION:

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.

PMID:
20810375
PMCID:
PMC3711561
DOI:
10.1001/jama.2010.1271
[Indexed for MEDLINE]
Free PMC Article

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