Neonatal Seizures Among Low-Risk Pregnancies at Term: Risk Factors and Adverse Outcomes

Objective: To examine risk factors and adverse outcomes for neonatal-maternal dyads among low-risk pregnancies at term with subsequent neonatal seizures.

Methods: United States vital statistics data sets were used for this retrospective study. Inclusion criteria were low-risk women (without hypertensive disease or diabetes) with nonanomalous singleton pregnancies, who delivered after labor at 37-41 weeks of gestation. The primary composite neonatal adverse outcome included 5-minute Apgar score less than 5, assisted ventilation longer than 6 hours, and neonatal death. A secondary outcome was composite maternal adverse outcome. Multivariable Poisson regression models with robust error variance were used, with adjusted relative risk (aRR) and 95% CI reported.

Results: Of 19.76 million live births during the study interval, 11.7 million (59.4%) met inclusion criteria. The rate of neonatal seizures after low-risk pregnancies delivered at term was 0.2 per 1,000 live births. The maternal risks factors associated with neonatal seizures included no prenatal care, smoking during pregnancy, being overweight or obese, and gestational age of 41 weeks. The strongest risk factors for neonatal seizures were chorioamnionitis (relative risk [RR] 5.04, 95% CI 4.40-5.77; aRR 3.27, 95% CI 2.84-3.76) and route of delivery, with operative vaginal (RR 3.62, 95% CI 3.20-4.09; aRR 3.02, 95% CI 2.66-3.43) and cesarean (RR 4.13, 95% CI 3.81-4.48; aRR 3.14, 95% CI 2.86-3.45) higher than spontaneous vaginal. Compared with neonates without seizures, those with seizures had higher risk of composite neonatal adverse outcome (RR 64.55, 95% CI 61.83-67.39; aRR 37.09, 95% CI 35.20-39.08). Compared with women who delivered neonates without seizures, those who delivered neonates with seizures had higher risk of composite maternal adverse outcome (RR 16.27, 95% CI 13.66-19.37; aRR 9.70, 95% CI 8.15-11.53).

Conclusion: We identified modifiable maternal risk factors associated with neonatal seizures among low-risk pregnancies at term. Though infrequent, neonatal seizures are associated with higher risk of adverse outcomes in neonatal-maternal dyads.