OBJECTIVE To analyze perinatal outcomes after maternal use of attention-deficit/hyperactivity disorder (ADHD) medication during pregnancy. METHODS The study included singletons born between 2006 and 2014 in Sweden. Data on prescription drug use, pregnancies, deliveries, and the newborn infants' health were obtained from the Swedish Medical Birth Register, the Prescribed Drug Register, and the Swedish Neonatal Quality Register. We compared infants exposed to ADHD medication during pregnancy with infants whose mothers never used these drugs and infants whose mothers used ADHD medication before or after pregnancy. Analyses were performed with logistic regression. RESULTS Among 964 734 infants, 1591 (0.2%) were exposed to ADHD medication during pregnancy and 9475 (1.0%) had mothers treated before or after pregnancy. Exposure during pregnancy increased the risk for admission to a NICU compared with both no use and use before or after pregnancy (adjusted odds ratio [aOR], 1.5; 95% confidence interval [CI], 1.3-1.7; and aOR, 1.2; 95% CI, 1.1-1.4, respectively). Infants exposed during pregnancy had more often central nervous system-related disorders (aOR, 1.9; 95% CI, 1.1-3.1) and were more often moderately preterm (aOR, 1.3; 95% CI, 1.1-1.6) than nonexposed infants. There was no increased risk for congenital malformations or perinatal death. CONCLUSIONS Treatment with ADHD medication during pregnancy was associated with a higher risk for neonatal morbidity, especially central nervous system-related disorders such as seizures. Because of large differences in background characteristics between treated women and controls, it is uncertain to what extent this can be explained by the ADHD medication per se.