Thomas Desplanches

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.