Antidepressant use in late gestation and risk of postpartum haemorrhage: a retrospective cohort study

Objective: To investigate the association between antidepressant use in late gestation and postpartum haemorrhage (PPH). Design: Retrospective cohort study. Setting: Tertiary teaching hospital in Adelaide, Australia. Population: A total of 30 198 women delivering between 2002 and 2008. Methods: Relative risks adjusted for maternal sociodemographics and comorbidities (aRRs) were calculated for PPH, comparing women with late-gestation exposure to antidepressants (n = 558), women with a psychiatric illness but no antidepressant use (n = 1292), and women with neither antenatal exposures (n = 28 348). Additional sensitivity analyses were undertaken, examining associations with severe PPH and postpartum anaemia. Main outcome measures: The primary outcome was PPH, defined as a recorded blood loss of ≥500 mL for vaginal deliveries and ≥1000 mL for caesarean sections. Secondary outcomes included severe PPH (≥1000 mL blood loss, irrespective of method of delivery), and the presence of postpartum anaemia (identified from hospital medical records). Results: Compared with unexposed controls, women exposed to antidepressants had an increased risk of PPH (aRR 1.53; 95% confidence interval, 95% CI 1.25–1.86), whereas no increased risk was observed for women with a psychiatric illness but no antidepressant use (aRR 1.04; 95% CI 0.89–1.23). In sensitivity analyses, late gestation antidepressant exposure was associated with an increased risk of severe PPH (aRR 1.84; 95% CI 1.39–2.44), as well as postpartum anaemia (aRR 1.80; 95% CI 1.46–2.22). Conclusions: Exposure to antidepressants in late gestation was associated with a significantly increased risk of PPH. Although potential confounding by unmeasured factors cannot be ruled out, these findings suggest a direct effect of antidepressant exposure on PPH. Tweetable abstract: Late gestation antidepressant exposure is associated with a significantly increased risk of postpartum haemorrhage.