By John C. Hobbins, MD
Professor, Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora
SYNOPSIS: Recently a randomized clinical trial has demonstrated that a greater threshold for second stage labor time in nulliparous patients can lead to a significant decrease in the need for and rate of cesarean sections.
SOURCE: Gimovsky AC, Berghella V. Randomized control trial of prolonged second stage: Extending the time limit vs usual guidelines. Am J Obstet Gynecol 2016;214:361.e1-6.
The record high cesarean section rate (CSR) of 32% set in 2009 was a stark contrast to what was considered ideal: the 20% CSR achieved in 1996. In 2012, the National Institute of Child Health and Development (NICHD) and the American Congress of Obstetrics and Gynecology organized a workshop with the explicit goal of producing ideas that would safely move the CSR back towards the levels in 1996. During deliberations the topic of time thresholds for the second stage of labor was discussed, rehashing the generally accepted axiom that it is ideal to limit second stage length to two hours or less. This dictum is supported almost solely by a study from over 60 years ago that demonstrated a drastic increase in rates of infant mortality in deliveries that exceeded the 2-hour limit. Review of contemporary data, however, has revealed that this may not necessarily be the case. In fact, the committee ruled that longer second stage times are acceptable and should be allowed.
These rulings were promptly included in the considerations of the 2014 Society of Maternal-Fetal Medicine (SMFM) Obstetric Care Consensus Report, in which “second stage arrest” was defined as prolongation of the second stage by more than three hours in nulliparous women without epidural anesthesia and four hours in nulliparous women with epidurals. In multipara, the second stage threshold was two hours without epidurals and three hours with the anesthetics.
Further testing this approach, Philadelphia-based investigators randomly assigned nulliparous patients who were undelivered after three hours with epidurals or two hours without epidurals to two groups. One group underwent expedited delivery by either instrumental delivery or cesarean section, while the other experienced extended labor of trying to deliver for another hour.
The study was limited, with just 78 patients partaking. The CSR for the extended labor group was 19.5% (8/41) and 43.2% (16/37) in the expedited delivery group. The authors determined that for every four nulliparous women who extended their second stage another hour, a cesarean section was avoided. The differences in neonatal outcomes as well as maternal morbidities were the same for both groups. The authors concluded that extension of the second stage of labor can significantly reduce the CSR.