Procedures
Inclusion took place in the immediate postpartum period from April 27, 2017, to April 2, 2019. The volume of bleeding was quantified for vaginal deliveries by using a graduated/marked collection bag and for caesarean deliveries, by aspiration and weighing the blood loss. PPH prevention and management followed the French clinical practice guidelines.11
The exposed group comprised the women who had had a primary PPH (≥500 mL in the 24 hours after delivery) and the unexposed group, which did not. For each woman with PPH, we planned to recruit 2 women without it: the ones immediately before and after the delivery of the woman with PPH.14 The investigator provided women with a written information sheet and obtained their written consent before their discharge.14
The study was registered at ClinicalTrials.gov (NCT 03120208).