Duration of the active phase of labor in spontaneous and induced labors.

Research paper by Tilde B TB Østborg, Pål R PR Romundstad, Torbjørn M TM Eggebø

Indexed on: 13 Oct '16Published on: 13 Oct '16Published in: Acta Obstetricia et Gynecologica Scandinavica


The aim of the study was to compare the duration of active phase of labor in women with spontaneous or induced start of labor.An observational cohort study was performed at Stavanger University Hospital in Norway between January 2010 and December 2013 and 19 524 women delivered during the study period. Data for the study were collected from an electronic birth journal. Women with previous cesarean section, multiple pregnancy, breech or transverse lie, preterm labor or prelabor cesarean section were excluded. Analyses were stratified between nulliparous and parous women. Active phase of labor was defined when contractions were regular; cervix effaced and dilated four cm. The main outcome measure was duration of active phase of labor.The active phase was longer in induced labors compared to labors with spontaneous onset in nulliparous women. The estimated median duration using survival analyses was 433 (95% CI 419-446) minutes in spontaneous vs. 541 (95% CI 502-580) minutes in induced labors (unadjusted hazard ratio 0.76 (95% CI 0.71 - 0.82) and adjusted hazard ratio 0.88 (95% CI 0.82-0.95). In parous women a one minus survival plot showed that induced labors had shorter duration before six hours in active labor, but after six hours induced labors had longer duration. The overall difference in parous women was small and probably of little clinical importance.Active phase of labor was longer in induced than spontaneous labors in nulliparous women. This article is protected by copyright. All rights reserved.