Pharmacological pain relief and postpartum bleeding in women with moderate or severe anemia: A cohort analysis of the WOMAN ‐2 trial

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OBJECTIVE: Pain relief could minimize blood loss by limiting the adrenaline stress response to fear and trauma during birth. We examined the association between pharmacological pain relief and postpartum bleeding in a large cohort of women giving birth with anemia in sub-Saharan Africa and South Asia. METHODS: We conducted a cohort analysis using data from the WOMAN-2 trial. Between August 2019 and September 2023, women with moderate or severe anemia who were giving birth vaginally were recruited from hospitals in Nigeria, Pakistan, Tanzania, and Zambia. Our exposure was receipt of pharmacological pain relief during birth. Our primary and secondary outcomes were calculated postpartum hemorrhage (PPH) (≥1000 mL estimated blood loss, which was calculated from peripartum change in hemoglobin concentration) and clinically diagnosed PPH (blood loss ≥500 mL or any blood loss causing hemodynamic instability), respectively. We used multilevel logistic regression to examine the association between pharmacological pain relief and postpartum bleeding outcomes, including a random effect for hospital and fixed effects for other potential confounders. RESULTS: Of 15 068 women recruited to the WOMAN-2 trial, 1810 women received pain relief (12.0%). Opioids were used most (n = 1344). Among women having an episiotomy, pain relief was used in 19% (Pakistan), 10% (Zambia), 4% (Nigeria), and 1% (Tanzania). Among women having an instrumental birth, pain relief was used in 21% (Pakistan, Nigeria, and Zambia) and 2% (Tanzania). The unadjusted odds ratios (ORs) were 0.76 (95% confidence interval [CI]: 0.58-1.00) for calculated PPH and 1.28 (95% CI: 0.99-1.67) for clinically diagnosed PPH. After adjusting for potential confounders, the OR for calculated PPH was 0.64 (95% CI: 0.49-0.82) and the OR for clinically diagnosed PPH was 0.89 (95% CI: 0.67-1.17). CONCLUSION: Pharmacological pain relief may reduce postpartum bleeding. Women giving birth vaginally in sub-Saharan Africa and South Asia rarely get pain relief, even when having surgical procedures.