Incidence of immediate postpartum hemorrhages in French maternity units: a prospective observational study (HERA study)

BACKGROUND: Most estimates of postpartum hemorrhage (PPH) are calculated from studies that use administrative or medical birth databases, and only a few from prospective observational studies. Our principal objective was to estimate the incidence of PPH according to their severity (mild or severe) in vaginal deliveries (>500 mL, ≥1000 mL) and cesareans (>1000 mL and ≥1500 mL). The secondary objectives were to describe the incidence of PPH according to maternity unit characteristics, causes, and types of PPH management. METHODS: This prospective observational study took place in French maternity wards. Women who gave birth at a term ≥ 22 weeks were eligible for the study. 182 maternity units participated in a study with prospective data collection from 1 February, 2011, to 31 July, 2011. The main outcome measure was PPH incidence. RESULTS: PPH incidence after vaginal delivery was 3.36 % [95 % CI: 3.25–3.47 %] and after cesareans 2.83 % [95 % CI: 2.63–3.04 %]. The incidence of severe PPH after vaginal delivery was 1.11 % [95 % CI: 1.05–1.18 %] and after cesareans 1.00 % [95 % CI: 0.88–1.13 %]. This incidence rate varied according to maternity unit characteristics. The principal cause of PPH for both modes of delivery was uterine atony (57.7 % for vaginal births and 66.3 % for cesareans). Vascular embolization was more frequent among women with cesareans (10.0 vs. 2.9 %), who also required transfusions more often (44.4 vs 12.7 %). CONCLUSIONS: The incidence of PPH was lower than the rate expected from the literature. Effective treatment of uterine atony and optimizing the identification of blood loss remain important priorities. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12884-016-1008-7) contains supplementary material, which is available to authorized users.