Postpartum hemorrhage risk reported higher in nulliparous women

The rate of postpartum hemorrhage (PPH) is increased among nulliparous women vs multiparous women, according to a recent study published in Preventive Medicine Reports.¹

PPH is defined as blood loss of 500 ml or more within 24 hours after birth. It is attributed to approximately 25% of maternal deaths worldwide and is a leading cause of maternal morbidity. The World Health Organization has reported 14 million PPH cases per year, leading to 127,000 deaths.

Concerns have arisen about the rising incidence of PPH, with rates up to 18% estimated among women with mixed parity. However, data about PPH incidence in nulliparous and multiparous women is currently lacking. Only a few studies have assessed PPH in nulliparous women and none have assessed incidence in multiparous women.

Understanding the impact of parity on PPH incidence may improve prediction models. Early detection and treatment are vital, as one study reported a decreased risk of severe PPH, postpartum laparotomy, and maternal death from bleeding following early treatment.² The rate of any of these outcomes decreased from 3.8% to 1.1% from intervention.

To evaluate differences in PPH incidence between nulliparous and multiparous women, investigators conducted a multicenter hospital-based retrospective cohort study.¹ Data was obtained from medical records at 13 maternal-child health care hospitals and 5 general hospitals within Hunan Province, South China.

Participants included pregnant women admitted to relevant health facilities between January 1, 2017, and December 31, 2018, giving birth at 28 weeks’ gestation or later. Relevant data included marital status, maternal age, gravidity, education, place of birth, type of pregnancy, mode of birth, antenatal care visits, birth weight, and gestational age.

Comorbidities were also assessed, including diabetes, anemia, gestational hypertension, hepatopathy, low platelet count, blood clot formation disorder, systemic infection, and more. Medical measures were also assessed, with variables reported as “yes” or “no.”¹

PPH was reported as the primary outcome of the analysis, defined by blood loss of at least 500 ml after childbirth. Blood loss of 500 to 999 ml was considered moderate PPH, while blood loss of 1000 ml or more was considered severe PPH. Hemoglobin below 110 g/L was used to determine anemia, while expert definitions were used to define additional comorbidities.

There were 144,845 postpartum women included in the final analysis, 41.9% of whom were nulliparous and 58.1% multiparous. Of women, 45% were aged 30 to 34 years, 98.5% were married or cohabiting, 64% had secondary school education, and 63.5% were primigravida. A normal vaginal delivery was reported in 55.7%.¹

PPH was reported in 1.9% of participants, with 1.3% having moderate PPH and 0.6% having severe PPH. The incidence of PPH was slightly increased in nulliparous women vs multiparous women, at 2.1% vs 1.7%, respectively.

Factors significantly related to PPH in all patients included gravidity, maternal age, antenatal care visits, type of pregnancy, model of birth, birth weight, hepatopathy, anemia, blood clod formation disorder, placental abruptions, general anesthesia use before birth, magnesium sulfate before birth, platelet transfusion, and more.¹

The odds of PPH were increased further in nulliparous women vs multiparous women from low antenatal care visits, anemia, soft birth canal avulsion, and erythrocyte suspension transfusion before childbirth. Adjusted odds ratios (aORs) were 2.90, 8.41, 4.01, and 48.67, respectively.

For multiparous women, factors increasing PPH more than in nulliparous women were cesarean section, placenta abruption, and general anesthesia administration before birth, with aORs of 5.81, 3.62, and 1.63, respectively. The area under the curve for predictive performance was 0.828 for the nulliparous group vs 0.833 for the multiparous group.

These results indicated increased incidence of PPH in nulliparous women vs multiparous women, with influencing factors varying by parity. Investigators concluded these results provide insight into different approaches for PPH based on parity to improve maternal-child safety.¹

References

1. Bestman PL, Nget M, Kolleh EM. A comparative analysis of Postpartum Hemorrhage incidence and influencing factors between nulliparous and multiparous women in Hunan Province, China: A multicenter retrospective cohort study. Preventive Medicine Reports. 2024;38. doi:10.1016/j.pmedr.2023.102580
2. Krewson C. Early detection needed to reduce postpartum hemorrhage mortalities. Contemporary OB/GYN. October 9, 2023. Accessed July 15, 2024. https://www.contemporaryobgyn.net/view/early-detection-needed-to-reduce-postpartum-hemorrhage-mortalities