Prenatal events and the risk of cerebral palsy in very low birth weight infants.

The purpose of this study was to analyze associations between prenatal factors and cerebral palsy in a geographically based cohort of very low birth weight infants. Cases (n = 80) and controls had birth weights of 500-1,500 g and were born in 1978-1989, to a resident of one of 17 counties in northwest North Carolina. Medical records were reviewed for data about prenatal and neonatal factors. Associations were analyzed separately for three clinical forms of spastic cerebral palsy (hemiplegia, diplegia, and quadriplegia) and for cerebral palsy with and without antecedent major cranial ultrasound abnormalities. The following factors were associated most strongly with an increased risk of cerebral palsy: multiple gestation, chorioamnionitis, maternal antibiotics, antepartum vaginal bleeding, and labor lasting less than 4 hours. Preeclampsia and delivery without labor were associated with a decreased risk. Evidence of confounding was found for each of these associations, except for those with chorioamnionitis and labor lasting less than 4 hours. The association with chorioamnionitis was stronger for diplegia (compared with hemiplegia and quadriplegia) and for cerebral palsy without major cranial ultrasound abnormalities. Associations with antepartum vaginal bleeding (increased risk) and preeclampsia (decreased risk) were stronger for cerebral palsy occurring with major cranial ultrasound abnormality.