OBJECTIVE This study evaluated the effects of prenatal antidepressant exposure on perinatal outcomes, congenital malformations, and early growth and development. METHOD Within a group-model health maintenance organization, all infants with apparent prenatal exposure to tricyclic or selective serotonin reuptake inhibitor (SSRI) antidepressants were frequency matched to an unexposed comparison group by year of birth, maternal age, and mother's lifetime use of antidepressant drugs and mental health care. A structured blind review of mothers' and infants' medical records examined perinatal outcomes, congenital malformations, and developmental delay. RESULTS Tricyclic antidepressant exposure was not associated with any significant difference in perinatal outcomes. Exposure to SSRIs was associated with a 0.9-week decrease in mean gestational age, a 175-g decrease in mean birth weight, and a 0.29 decrease in mean Apgar score at 5 minutes, but differences in birth weights and Apgar scores were not significant after adjustment for gestational age. Differences in gestational age and birth weights were unrelated to length of exposure, but differences in Apgar scores were limited to those with third-trimester exposure. Neither tricyclic antidepressant nor SSRI exposure was significantly associated with congenital malformations or developmental delay. CONCLUSIONS The authors found no association between tricyclic antidepressant or SSRI exposure and either congenital malformations or developmental delay. SSRI exposure during pregnancy was associated with earlier delivery and consequent lower birth weight. Third-trimester SSRI exposure was also associated with lower Apgar scores. Women considering taking SSRIs during pregnancy may balance any higher fetal risk against the risk of persistent or recurrent depression.