Risk factors for postpartum haemorrhage in twin pregnancies and haemorrhage severity

Introduction: This study evaluated risk factors for postpartum haemorrhage (PPH) in twin pregnancies, particularly factors associated with major PPH (blood loss of >1000 mL), to facilitate identification of high-risk twin pregnancies.Methods: This retrospective cohort study included all women with twin pregnancies who delivered at a tertiary obstetric unit in Hong Kong from 2009 to 2018 and experienced PPH (blood loss of >_500 mL). Postpartum haemorrhage was classified using three thresholds for blood loss volume: >_500 mL (all PPH), >1000 mL (major PPH), and >1500 mL (severe PPH). Risk factors for each threshold of PPH were analysed.Results: In total, there were 680 twin pregnancies. The overall incidence of all PPH (>_500 mL) in this cohort was 27.8%, including minor PPH (500-1000 mL, 20.1%), major but not severe PPH (1001-1500 mL, 4.4%), and severe PPH (>1500 mL, 3.2%). Logistic regression analysis showed that general anaesthesia and the use of oxytocin were significant risk factors for all PPH (>_500 mL); general anaesthesia, in vitro fertilisation, antepartum haemorrhage, placental abruption, and placenta praevia were significant risk factors for major PPH (>1000 mL); in vitro fertilisation, placenta praevia, and obesity were significant risk factors for severe PPH (>1500 mL).Conclusion: Women with twin pregnancies who have obesity, conception by in vitro fertilisation, or placenta praevia exhibit a high risk of severe PPH. They should deliver in obstetric units with readily available blood product transfusions and the appropriate expertise for prompt management of severe PPH.