PRENATAL MAGNESIUM-SULFATE EXPOSURE AND THE RISK FOR CEREBRAL-PALSY OR MENTAL-RETARDATION AMONG VERY-LOW-BIRTH-WEIGHT CHILDREN AGED 3 TO 5 YEARS

Objective.-To examine the relationship between prenatal magnesium sulf ate exposure and the risk for cerebral palsy (CP) or mental retardatio n (MR) among very low-birth-weight (VLBW; <1500 g) children. Secondari ly, to investigate the effect of prenatal magnesium sulfate exposure o n VLBW infant mortality. Design.-Cohort study with follow-up to 1 year of age; a subset followed up to 3 to 5 years. Setting.-Twenty-nine Ge orgia counties, including the Ei-county Atlanta metropolitan area. Par ticipants.-All VLBW births (N=1097) occurring during 2 years (1986-198 8); all metropolitan Atlanta VLBW neonates who survived infancy (N=519 ). Main Outcome Measures.-lnfant mortality as determined from vital st atistics records, Development of CP or MR by 3 to 5 years of age among metropolitan Atlanta VLBW survivors as determined from the Metropolit an Atlanta Developmental Disabilities Surveillance Program. Results.-F or the entire cohort, there was no association between prenatal magnes ium sulfate exposure and infant mortality (adjusted rate ratio, 1.02; 95% confidence interval [CI], 0.83-1.25). Among Atlanta-born survivors , those exposed to magnesium sulfate had a lower prevalence of GP or M R than those not exposed (CP: magnesium sulfate, 0.9%, no magnesium su lfate, 7.7%, crude odds ratio [OR], 0.11, 95% CI, 0.02-0.81; MR: magne sium sulfate, 1.8%, no magnesium sulfate, 5.8%, crude OR, 0.30, 95% CI , 0.07-1.29). Multivariable adjustment had no appreciable effect on th e ORs for CP or MR, but the Cls included 1.0. Conclusions.-A reduced r isk for CP, and possibly MR, among VLBW children is associated with pr enatal magnesium sulfate exposure. The reduced risk for childhood CP o r MR does not appear to be due to selective mortality of magnesium sul fate-exposed infants.