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.