OBJECTIVES: There has been an increase in the diagnosis of depression and the use of antidepressants, especially in women of childbearing age, in the past decade. This has drawn attention to the potential impact of depression and antidepressants on pregnancy and fetal development. To determine the impact of prenatal exposure to antidepressant on the risk of adverse birth outcomes. METHODS: The study was conducted using a population-based cohort including all singletons deliveries in years 2008 to 2014 in SC Medicaid population. Information on antidepressant medication and diagnosis of depression and birth outcomes were obtained from South Carolina Medicaid database and birth certificates. The exposed group comprised children of mothers who had a diagnosis of depression and used antidepressants at any time during their pregnancy. The reference group comprised children of mothers who had a diagnosis of depression but did not use any antidepressants during pregnancy. We estimated the association using Marginal Structural Models. RESULTS:  Approximately 107, 683 women had a diagnosis of depression in the SC Medicaid population. After applying the study inclusion and exclusion criteria, we got the study sample of 4,450 women. And approximately 36% women received antidepressants during pregnancy. In our study we found that the odds of preterm delivery were 1.72 times (95% CI: 1.63 – 1.79) in the group that received antidepressants during pregnancy as compared to those who did not. Prenatal exposure to antidepressants also increased the odd of having low birth weight/small for gestational age 1.63 times (95%CI: 1.53 – 1.73) and the increased odds of NICU admission by 1.66 times (95% CI: 1.58 – 1.73). CONCLUSIONS: In conclusion we found that prenatal exposure to antidepressants is significantly associated with a higher risk of adverse birth outcomes such as preterm delivery, low birth weight/small for gestational age, and NICU admissions.