Postpartum hemorrhage after SARS‐CoV‐2 infection in pregnancy: A Scandinavian register‐based cohort study

Introduction The aim was to evaluate whether SARS‐CoV‐2 infection during pregnancy was associated with severe postpartum hemorrhage (PPH), as SARS‐CoV‐2 infection has been shown to affect the coagulation system. Material and Methods In this national register‐based cohort study in Sweden, Denmark, and Norway, we studied the association between severe PPH according to a registered positive test for SARS‐CoV‐2 during pregnancy between March 1, 2020 and March 31, 2023 using logistic regression analyses to estimate odds ratios (ORs) with 95% confidence intervals (CI). Country‐specific estimates of association were combined in random effects meta‐analyses. The primary outcome was severe PPH, defined as a blood loss >1500 mL and/or receiving a blood transfusion. Results We included 542 394 singleton deliveries (264 804 in Sweden, 143 775 in Denmark, and 133 815 in Norway), of which 62 606 women (11%) had a positive SARS‐CoV‐2 test during pregnancy, and 20 786 (3.8%) deliveries were registered with a severe PPH. Overall, we observed no association between testing positive for SARS‐CoV‐2 during pregnancy and severe PPH (combined adjusted OR 1.04; 95% CI: 0.96–1.12). The results were similar for different calendar periods corresponding to dominant SARS‐CoV‐2 variants. We did, however, observe an association between severe PPH and women testing positive within 7 days before delivery (combined adjusted OR 1.30; 95% CI: 1.10–1.53). Conclusions There was no association identified between SARS‐CoV‐2 test positivity and PPH of >1500 mL and/or blood transfusion in pregnant women from three Scandinavian countries. However, we observed a 30% higher odds of severe PPH among pregnant women who tested positive within one week before delivery.