Risk Factors for Postpartum Hemorrhage Following Vaginal Deliveries in China: A Case-Control Study of Second Births After IUD Removal.

Objective: This study aims to evaluate the predictive value of risk factors for postpartum hemorrhage (PPH) following vaginal delivery, with a special focus on the impact of intrauterine device (IUD) usage in the context of recent policy changes allowing more childbirths in China.

Methods: A total of 6879 women who underwent vaginal deliveries from January 2021 to December 2023 in the Lianyungang regional maternal care system and met the inclusion and exclusion criteria were enrolled. A case-control design was employed, comprising 524 women with PPH (blood loss ≥500 mL) 24h after giving birth and an equal number of controls (blood loss <500 mL) matched on a 1:1 ratio. Univariate and multivariate logistic regression analyses, alongside ROC curve analysis, were conducted to identify risk factors for PPH.

Results: Univariate analysis revealed significant differences in age (OR = 1.86, 95% CI: 1.35-2.57, P < 0.01), number of miscarriages (OR = 1.97, 95% CI: 1.46-2.65, P < 0.001), gestational week, number of fetuses, weight of the second child (OR = 10.78, 95% CI: 7.88-14.75, P < 0.001), placental adhesion, and uterine atony (OR = 2.40, 95% CI: 1.60-3.61, P < 0.001). No significant differences were observed regarding occupation, educational level, mode of first delivery, IUD use and duration, and presence of gestational diabetes or hypertension (P > 0.05). Multivariate logistic regression identified age, number of miscarriages, weight of the second child, and uterine atony as independent risk factors for PPH (P < 0.05). ROC curve analysis showed that the combined predictive value of these factors was superior, with an AUC of 0.805 for the combined predictive model.

Conclusion: PPH is influenced by advanced maternal age, multiple miscarriages, high birth weight, and uterine atony. IUD use may not independently impact the likelihood of PPH under the conditions studied.