Study on the relationship between neonatal body weight and postpartum hemorrhage in vaginal delivery based on propensity score matching

Objective: To explore the relationship between neonatal body weight and postpartum hemorrhage in vaginal delivery based on propensity score matching. Methods: A total of 10 046 women who delivered vaginally were selected as the study subjects,and divided into the non-macrosomia group (neonatal body weight<4 000 g) and macrosomia group (neonatal body weight ≥4 000 g) according to neonatal body weight.The 1∶1 propensity score in two groups was matched,the relationship between neonatal body weight and postpartum hemorrhage was analyzed by logistic regression,and the relationship between neonatal body weight and postpartum hemorrhage was further stratified according to the results of logistic regression analysis. Results: A total of 751 pairs of women were matched with propensity scores,and the general characteristics of the two groups were basically balanced.The incidence of postpartum hemorrhage was 197(13.1%) among the 1 502 women who were matched.The differences of the pregnancy,parity,prenatal fever,macrosomia,hypertension,and placental delivery mode between the general characteristics of postpartum hemorrhage and non-postpartum hemorrhage after matching were statistically significant(P<0.05 to P<0.01).The results of logistic regression analysis showed that the risk of postpartum hemorrhage in macrosomia was 1.994 times higher than that in nonmacrosomia infants(OR=1.994,95%CI:1.448-2.746,P<0.01)。The four percentiles of neonatal body weight (P₅,P₂₅,P₇₅,P₉₅) were 2 035.8 g,2 600.0 g,4 130.0 g,4 398.5 g,respectively.According to the three values of P₂₅,4 000 g and P₇₅,the neonatal body weight was divided into four groups,and after adjusting for possible confounding factors,the risk of postpartum hemorrhage in the neonatal body weight 4 000-<4 130 g group and neonatal body weight ≥4130 g group were 9.047 times and 11.235 times higher than that in neonatal body weight<2 600 g group. Conclusions: Neonatal body weight is an important influencing factor of postpartum hemorrhage,and the risk of postpartum hemorrhage increases with the increase of neonatal body weight.