Identifying the effect of inherited bleeding disorders on the development of postpartum hemorrhage: a population-based, retrospective cohort study

Background — Women with inherited bleeding disorders (IBD) have an increased risk of postpartum hemorrhage (PPH). However, the impact of other maternal pre-delivery risk factors, including anemia, on the association between IBD and maternal bleeding remains poorly understood. Additionally, studies examining potential pathways linking IBD and PPH are limited.

Objective — To determine the risk of PPH associated with IBD.

Methods — A retrospective cohort study was conducted using data held within ICES (formerly: the Institute for Clinical Evaluative Sciences). Women with an in-hospital, live or stillborn delivery, between January 2014 and December 2019 were included. Poisson regression with robust error variance was used to determine risk (RR) and 95% confidence intervals (CIs) of PPH among women with or without an IBD diagnosis. Models were stratified for primiparous and multiparous women.

Results — Among the total population of 601,773 women, 29,661 (4.93%) experienced PPH. Multivariate models demonstrated that IBD was an independent risk factor for PPH among both the total cohort (adjusted RR [aRR] = 1.26, 95% CI 1.08,1.46) and primiparous women (aRR = 1.36, 95% CI 1.12, 1.66). Among multiparous women, prior PPH was associated with increased risk of PPH (aRR = 8.65, 95% CI 8.32, 8.99) while IBD had no effect (aRR = 1.1, 95% CI 0.86, 1.4). Pre-delivery anemia, placental conditions, multifetal gestation, and induction of labour were associated with increased PPH risk among all cohorts.

Conclusions — IBD significantly increases the risk of PPH. Management of delivery should be based on individualized assessment of risk factors to ensure optimal maternal outcomes.