OBJECTIVE: To estimate maternal and perinatal outcomes among women with increasing duration of the second stage of labor.
METHODS: A population-based cohort study was conducted among women with low-risk, singleton, vertex, nonanomalous deliveries at or after 37 weeks of gestation between 1988 and 2006. Individual maternal (hemorrhagic, infectious, and traumatic), perinatal (birth depression, infectious, and traumatic), and composite outcomes were evaluated with increasing duration of the second stage. Logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals for all outcomes and to account for confounding variables, including maternal age, prelabor rupture of membranes, augmentation of labor, antibiotics in labor, regional analgesia, gestational age, birth weight, and year of birth. Effect modification caused by method of delivery was considered.
RESULTS: From a population of 193,823 women, 121,517 women met inclusion and exclusion criteria, of whom 63,404 (52%) were nulliparous. There was an increase in risk of maternal obstetric trauma, postpartum hemorrhage, puerperal febrile morbidity and composite maternal morbidity, and low 5-minute Apgar score, birth depression, admission to the neonatal intensive care unit, and composite perinatal morbidity among both nulliparous women and multiparous women, with increasing duration of the second stage of labor. Method of delivery only modified the effect of duration of second stage among nulliparous women.
CONCLUSION: Risks of both maternal and perinatal adverse outcomes rise with increased duration of the second stage, particularly for duration longer than 3 hours in nulliparous women and longer than 2 hours in multiparous women.
LEVEL OF EVIDENCE: II
Risks of maternal and perinatal adverse outcomes in both nulliparous and multiparous women rise with increased duration of the second stage of labor.
From the 1Department of Obstetrics and Gynaecology, the 2Perinatal Epidemiology Research Unit, and the 3Departments of Anaesthesia and 4Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada.
Dr. Allen is supported by a Clinical Research Scholar Award from Dalhousie University and by a New Investigator Award of the Canadian Institutes of Health Research.
The authors thank the Reproductive Care Program of Nova Scotia for providing access to the data.
Corresponding author: Victoria M. Allen, Department of Obstetrics and Gynaecology, IWK Health Centre, Room G2141, 5850/5980 University Avenue, Halifax, Nova Scotia, Canada B3K6R8; e-mail: firstname.lastname@example.org.
Financial Disclosure The authors did not report any potential conflicts of interest.