Timing of selective serotonin reuptake inhibitor use and risk for preterm birth and related adverse events

Purpose There is uncertainty around the safety of SSRIs for treating depression during pregnancy. We aimed 1) to address confounding by indication, as well as socioeconomic and environmental factors associated with depression and 2) evaluate associations of timing of SSRI exposure in pregnancy with the risk of preterm birth and related outcomes (small for gestational age and low birthweight) among women with depression before pregnancy. Methods We conducted propensity score-adjusted regression to calculate odds ratios (OR) of preterm birth, small for gestational age, and low birth weight. We accounted for maternal/pregnancy characteristics, pre-pregnancy comorbidity/depression severity, social vulnerability, rural health disparity, and pre-natal depression severity. We additionally conducted a drug-specific analysis and assessed the impact of other classes of antidepressants within our cohort of interest. Results Among women with a history of depression, we identified women with indication of depression ≤ 180 days before pregnancy (n=6,408). Women with no SSRI order during pregnancy (n=3,122) constituted the unexposed group (no SSRI exposure group). The late SSRI exposure group consisted of women with an SSRI order after the first trimester (n=2,596). The early-only SSRI exposure group consisted of women with SSRI orders only in the first trimester (n=691). Late SSRI exposure group had an increased risk of preterm birth of OR=1.7 ([1.3,2.2], p<0.0001), and low birth weight of OR = 1.7 ([1.3,2.4], p<0.001), relative to the no SSRI exposure group. Conclusions These findings suggest associations between preterm birth/low birthweight and SSRI exposure is dependent on exposure timing during pregnancy. Small for gestational age is not associated with SSRI exposure.