, according to researchers.
The researchers performed a retrospective analysis of more than 103,000 pregnancies from the Consortium on Safe Labor, a study of electronic medical records from 12 U.S. sites from 2002 to 2008, according to a study published in Obstetrics & Gynecology.
The duration of the second stage was calculated from the time of 10-cm cervical dilation to the time of birth. The researchers stratified the results into nulliparous women who did or did not receive an epidural, and multiparous women who did or did not receive an epidural.
For nulliparous women, rates of spontaneous vaginal birth (rather than operative vaginal birth or cesarean delivery) without morbidity increased slightly in the second half-hour over the first, then decreased. Rates decreased steadily for multiparous women. Both decreases occurred regardless of epidural status. Deliveries with morbidity varied, to as high as a 12.3% likelihood that a nulliparous woman with an epidural would deliver with maternal or neonatal morbidity or mortality between 3 hours’ and 6 hours’ second-stage duration.
The researchers noted the various society recommendations for when to diagnose second-stage arrest, but concluded: “In our study, we did not observe an inflection at a particular hour mark. ... Ultimately the willingness to accept a certain percentage risk of morbidity to achieve vaginal delivery is up to the woman and clinician.”
The authors reported having no disclosures.
SOURCE: Grantz KL et al. Obstet Gynecol. 2018 Feb;131(2):345-53.