Major postpartum haemorrhage after frozen embryo transfer: A population-based study

Objective: To investigate the effect on major postpartum haemorrhage (PPH) of mode of conception, differentiating between naturally conceived pregnancies, fresh embryo in vitro fertilisation (fresh-IVF) and frozen embryo transfer (frozen-IVF). Design: Retrospective cohort study. Setting: The French Burgundy Perinatal Network database, including all deliveries from 2006 to 2020, was linked to the regional blood centre database. Population or sample: In all, 244 336 women were included, of whom 240 259 (98.3%) were singleton pregnancies. Methods: The main analyses were conducted in singleton pregnancies, including 237 608 naturally conceived, 1773 fresh-IVF and 878 frozen-IVF pregnancies. Multivariate logistic regression models adjusted on maternal age, body mass index, smoking, parity, induction of labour, hypertensive disorders, diabetes, placenta praevia and/or accreta, history of caesarean section, mode of delivery, birthweight, birth place and year of delivery, were used. Main outcome measures: Major PPH was defined as PPH requiring blood transfusion and/or emergency surgery and/or interventional radiology. Results: The prevalence of major PPH was 0.74% (n = 1749) in naturally conceived pregnancies, 1.92% (n = 34) in fresh-IVF pregnancies, and 3.30% (n = 29) in frozen-IVF pregnancies. The risk of major PPH was higher in frozen-IVF pregnancies than in both naturally conceived pregnancies (adjusted odds ratio [aOR] 2.63, 95% CI 1.68-4.10) and fresh-IVF pregnancies (aOR 2.78, 95% CI 1.44-5.35). Conclusions: We found that frozen-IVF pregnancies have a higher risk of major PPH and they should be subject to increased vigilance in the delivery room.