Incidence and risk factors for postpartum hemorrhage among transvaginal deliveries at a tertiary perinatal medical facility in Japan.

Postpartum hemorrhage (PPH) remains a leading cause of maternal death worldwide, and it is important to understand the relative contributions of different risk factors. We assessed the incidence of these among cases of transvaginal delivery. Between June 2013 and July 2016, a prospective cohort study was conducted at a tertiary perinatal medical facility in Japan. Women were administered a questionnaire to ascertain risk factors for PPH, defined as a blood loss of 1,000 ml or more assessed using a calibrated under-buttocks drape and collection vessel at childbirth. We analyzed 1,068 transvaginal deliveries of singleton pregnancies. The incidence of PPH was 8.7%, and of severe PPH (1,500 ml blood loss or more) was 2.1%. Risk factors for postpartum hemorrhage among the deliveries were: fetal macrosomia (over 4000 g); pregnancy-induced hypertension; pregnancy generated by assisted reproductive technology; severe vaginal or perineal lacerations; and weight gain over 15 kg during pregnancy. Such high weight gain significantly increased the incidence of PPH compared with women showing less than 10 kg weight gain during pregnancy. Monitoring these identified risk factors could enable extra vigilance during labor, and preparedness for managing PPH in all women giving birth