Impact of Maternal Weight and Gestational Weight Gain on Postpartum Hemorrhage and Adverse Outcomes: A Case–Control Study

Abstract

Objective: To assess the impact of maternal weight on postpartum hemorrhage (PPH) and other adverse outcomes at Siriraj Hospital. Materials and Methods: We conducted a retrospective chart review of 835 women who underwent spontaneous vaginal deliveries between January 2019 and August 2020. The study group comprised pregnant women experiencing PPH (167 out of 835), whereas the control group included pregnant women without PPH (668 out of 835). We documented demographic information, maternal medical complications, estimated blood loss, causes of PPH, neonatal outcomes, and other maternal adverse outcomes. Results: Baseline characteristics such as maternal age, pre-existing medical conditions, pre-pregnancy body mass index, total pregnancy weight gain, estimated blood loss, anemia, gestational age at delivery, and neonatal outcomes were not significantly different between the two groups. Mothers with excessive weight gain had a significantly greater incidence of PPH compared with those without PPH (41.9%, 70/167 vs 27.1%, 181/668; P = 0.0001). Similarly, maternal anemia (hematocrit < 33%) was more common in the PPH group (28.7%, 48/167) than in the non-PPH group (20.4%, 136/668; P = 0.019). Fetal macrosomia (neonatal weight > 4000 g) was also observed more frequently among women with PPH (3.0%, 5/167) compared with those without PPH (0.9%, 6/668; P = 0.049). These differences were statistically significant. Multiple logistic regression analysis revealed that both excessive gestational weight gain and maternal anemia were independently associated with PPH. Maternal anemia remained the strongest predictor, with an adjusted odds ratio (aOR) of 1.86 (95% CI 1.24–2.79; P = 0.003), while excessive gestational weight gain also showed a significant association (aOR) = 1.64, 95% CI 1.08–2.51; P = 0.021). Conclusion: PPH was not associated with overweight or obesity. However, it was correlated with excessive gestational weight gain during pregnancy and maternal anemia. Clinical Trial Registration: Thai Clinical Trials Registry (TCTR) 20220919004.