Association between intravenous fluids during labour and primary postpartum haemorrhage: A retrospective cohort study

Objective: To evaluate whether the administration of high-volume intravenous (IV) fluids during labour (≥ 2500 mL) increases the risk of primary postpartum haemorrhage (PPH) and other adverse outcomes for women with a term, singleton pregnancy, in comparison to low-volume IV fluids during labour (<2500 mL). Design: Retrospective cohort study Setting: Tertiary referral hospital in Sydney, Australia Sample: 1023 women with a live singleton fetus in a cephalic presentation; planning a vaginal birth; and admitted for labour and birth care between 37 - 42 weeks gestation. Methods: The study factor was IV fluids during labour. Birth and postnatal data were obtained from electronic medical records and paper fluid order documentation. Multivariable logistic regression and multiple imputation were used to explore the relationship between volume of IV fluids in labour and PPH. Main outcome measures: The primary outcome was primary PPH ≥ 500mL. Secondary outcomes included caesarean section and major perineal injury. Results: 1023 participants were included of which 339 had a primary PPH (33.1%). There was no association between high-volume IV fluids and PPH after adjusting for demographic and clinical factors (Adjusted odds ratio [OR ]1.02 95% confidence interval [95%CI] 0.72, 1.44). However, there was a positive association between high-volume IV fluids and caesarean section (OR 1.99; 95%CI 1.4, 2.8). Conclusion: These findings are important to further knowledge relating to administration of IV fluids in labour and the potential impact of this common practice. It identifies future research priorities around documentation of IV fluids and their relationship with pregnancy and perinatal outcomes.