Trends in severe postpartum haemorrhage among nulliparous women with spontaneous onset of labour: A population‐based cohort study

Abstract Objective To investigate the incidence of severe postpartum haemorrhage among nulliparous women with a spontaneous onset of labour at term from 2000 to 2020. Design Population‐based cohort study. Setting National, using the Medical Birth Registry of Norway. Population Women ( n = 330 244) who gave birth to their first singleton child in a cephalic presentation after a spontaneous onset of labour at term. Methods Cross‐tabulations and regression analysis with generalised linear models were used to assess time trends and adjust for potential confounding factors. We also stratified the analyses by maternal age groups, obstetric interventions, mode of delivery and institution size. Time trends were analysed using periods of 5 or 6 years as a unit, and the period from 2000 to 2004 was used as the reference. Main outcome measures Severe postpartum haemorrhage (PPH) was defined as blood loss of >1500 mL within 24 h and/or in combination with blood transfusion. Results Severe PPH occurred in 7601/330 244 (2.30%) women. The incidence increased from 1.24% in 2000–2004 to 3.83% in 2015–2020 (adjusted relative risk, aRR 2.90; 95% CI 2.70–3.12). Changes in maternal characteristics or obstetric interventions did not explain the increase, and we found similar increases across institutions of all sizes. Conclusions The incidence of severe PPH among nulliparous women increased almost threefold over 21 years. The current high incidence warrants urgent efforts to assess unknown risk factors, the health care provided and health system factors that may contribute to the increase, to inform improvements in care.