Duration of Second Stage of Labour at Term and Pushing Time: Risk Factors for Postpartum Haemorrhage

Background: Prolonged labour is associated with increased risk of postpartum haemorrhage (PPH), but the role of active pushing time and the relation with management during labour remains poorly understood. Methods: A population-based cohort study from electronic medical record data in the Stockholm-Gotland Region, Sweden. We included 57 267 primiparous women with singleton, term gestation, livebirths delivered vaginally in cephalic presentation in 2008-14. We performed multivariable Poisson regression to estimate the association between length of second stage, pushing time, and PPH (estimated blood loss > 500 mL during delivery), adjusting for maternal, delivery, and fetal characteristics as potential confounders. Results: The incidence of PPH was 28.9%. The risk of PPH increased with each passing hour of second stage: compared with a second stage < 1 h, the adjusted relative risk (RR) for PPH were for 1 to < 2 h 1.10 (95% confidence interval (CI) 1.07, 1.14); for 2 to < 3 h 1.15 (95% CI 1.10, 1.20); for 3 to < 4 h 1.28 (95% CI 1.22, 1.33); and for >= 4 h 1.40 (95% CI 1.33, 1.46). PPH also increased with pushing time exceeding 30 min. Compared to pushing time between 15 and 29 min, the RR for PPH were for < 15 min 0.98 (95% CI 0.94, 1.03); for 30-44 min 1.08 (95% CI 1.04, 1.12); for 45-59 min 1.11 (95% CI 1.06, 1.16); and for >= 60 min 1.20 (95% CI 1.15, 1.25). Conclusions: Increased length of second stage and pushing time during labour are both associated with increased risk of PPH.