OBJECTIVE: To investigate whether exposure to selective serotonin reuptake inhibitors (SSRIs) in early pregnancy is associated with miscarriage.

METHODS: This was a nationwide cohort study identifying all registered pregnancies in Denmark from 1997 to 2010. All births were identified using the Medical Birth Registry, and all records of induced abortion or miscarriage were gathered from the National Hospital Register. Data on SSRI use were gathered from the National Prescription Register. Cox proportional hazard regression models were used to calculate the hazard of miscarriage in women exposed to an SSRI in early pregnancy and the hazard of miscarriage in women discontinuing treatment before pregnancy.

RESULTS: We identified 1,279,840 pregnancies (911,569 births, 142,093 miscarriages, 226,178 induced abortions). Of the 22,884 exposed to an SSRI during the first 35 days of pregnancy, 12.6% (2,883) ended in miscarriage compared with 11.1% among unexposed. The adjusted hazard ratio of having a miscarriage after exposure to an SSRI was 1.27 (95% confidence interval [CI] 1.22-1.33) compared with unexposed. Women discontinuing SSRI treatment 3-12 months before pregnancy also had an increased hazard ratio of having a miscarriage compared to unexposed (1.24, 95% CI 1.18-1.30).

CONCLUSION: Women exposed to SSRIs during early pregnancy were at increased risk of miscarriage as were women discontinuing SSRI treatment before pregnancy, and these risks were similar. Therefore, treatment with SSRIs during pregnancy should not be discontinued as a result of fear of miscarriage. LEVEL OF EVIEDENCE:: II.