Comparative evaluation of prophylactic strategies for postpartum hemorrhage in vaginal delivery

To compare the efficacy of different prophylactic oxytocin regimens in preventing postpartum hemorrhage (PPH) after vaginal delivery.

Single-center retrospective cohort study including all vaginal deliveries between February 1, 2022, and December 31, 2023, at a tertiary referral unit. Throughout the study period, the local protocol for PPH prevention in vaginal delivery was changed from oxytocin 10 IU intramuscular injection (IM) to 5 IU intravenous bolus (IV) and eventually to 10 IU IV. Data regarding base maternal characteristics, pregnancy course, labor, and maternal outcomes were retrospectively collected from institutional labor ward registries. The incidence of PPH was compared among the three historical cohorts who received different oxytocin regimens (10 IU IM, group A; 5 IU IV, group B; and 10 IU IV, group C) following propensity score matching for those variables that proved to be significantly associated with PPH.

During the study period, 3850 women had a vaginal birth at our tertiary care unit (1245 in the 10 IU IM group, 1291 in the 5 IU IV group and 1314 in the 10 IU IV group) and were enrolled in the study population. Of these, 688 (17.8%) had PPH. At multivariable logistic regression nulliparity, second-degree or higher perineal tears, episiotomy, manual placental removal, birth weight, and multiple gestation appeared to be independently associated with PPH. PPH incidence was then compared among the groups following 1:1 propensity score matching for the above cited factors and appeared significantly higher with the use of 10 IU IM (group A) versus 5 IU IV (group B) oxytocin (21.3% versus 11.0%; P < 0.001) and versus 10 IU IV (group C) (22.1% versus 16.8%; P = 0.033); non-significant differences between the incidence of PPH were observed when comparing the two regimens of IV administration.

Intravenous administration of 5 IU or 10 IU is more effective than IM administration of 10 IU in reducing the incidence of PPH after vaginal deliveries. The efficacy of the two IV regimens appears similar.