This Practice Advisory has been endorsed by the American College of Nurse-Midwives and the Society for Maternal-Fetal Medicine.
A multicenter, pragmatic randomized controlled trial of immediate compared to delayed pushing in the second stage of labor was published in the Journal of the American Medical Association on October 9th, 2018 (1). Twelve thousand and eighty-eight patients were screened for inclusion between May 2014 and November 2017 at 6 regionally-representative centers in the United States. Two thousand, four hundred and fourteen nulliparous women with neuraxial anesthesia (20%) met inclusion criteria and agreed to participate, and 2404 (99.6%) completed the trial. Women were randomly assigned to begin pushing at complete dilation (immediate group, n=1200) or delay pushing for 60 minutes unless they had an urge to push or were instructed to do so by their health care provider (delayed group, n=1204).
After a planned second interim data and safety monitoring analysis at 75% recruitment, the study was stopped due to no difference in mode of delivery between the two groups and concern for increased morbidity in the delayed pushing group. There was no significant difference in the rate of spontaneous vaginal delivery between groups (immediate group 85.9% vs. delayed group 86.5%, RR 0.99, 95% CI 0.96 – 1.03, p=0.67). Women in the immediate group had a shorter mean second stage duration compared to delayed (102.4 vs. 134.2 minutes, respectively, p<0.001), and longer mean duration of pushing (83.7 vs. 74.5 minutes, respectively, p=0.005). In addition, the study found that women in the immediate pushing group had lower rates of chorioamnionitis (6.7% vs. 9.1%, RR 0.7, 95% CI 0.6 – 0.9, p=0.005) and postpartum hemorrhage (2.3% vs. 4.0%, RR 0.6, 95% CI 0.3 – 0.9, p=0.03) compared to those in the delayed group. There was no difference in the rates on the composite neonatal morbidity between the groups (7.3% vs. 8.9%, RR 0.8, 95% CI 0.6 – 1.1, p=0.16) or any perineal lacerations (45.9% vs. 46.4%, RR 0.99, 95% CI 0.95 – 1.04, p=0.69). However, women in the immediate pushing group delivered neonates with a lower rate of acidemia (0.8% vs. 1.2%, RR 0.7, 95% CI 0.6 – 0.9, p=0.01), but had higher rates of third-degree perineal lacerations (5.3% vs. 4.3%, RR 1.2, 95% CI 1.0 – 1.4, p=0.02). Subgroups analyses demonstrated that the equivalence in spontaneous vaginal delivery rate between the groups was not affected by fetal station, head position, approaches to pushing or study site.
Current recommendations from the American College of Obstetricians and Gynecologists are that in the absence of an indication for an expeditious delivery, women, particularly nullipara with neuraxial anesthesia, can be offered a period of rest of 1-2 hours before pushing (2). This recommendation was based on the best available, yet limited evidence at the time, and is founded on the theory that a rest period allows the fetus to passively rotate and descend while conserving the woman’s energy for pushing efforts. However, the current findings by Cahill et al, reinforce much of the preceding body of medical literature examining the overall length of the second stage of labor and rates of maternal and neonatal adverse outcomes (3-5). A prior meta-analysis among high-quality trials comparing immediate to delayed pushing found no difference in the rates of spontaneous vaginal birth (54.9% vs. 59.0%, RR 1.07, 95% CI 0.98 – 1.26) (6). Observational studies have demonstrated consistent uniform relationship between length of second stage of labor and risk of maternal and neonatal morbidity (4-6). When considering the newly available evidence from Cahill 2018 with the existing body of literature that demonstrates no increase in the rate of a spontaneous vaginal delivery but an increase in morbidity in the delayed pushing group, it is reasonable to choose immediate over delayed pushing in nulliparous patients with neuraxial anesthesia. Prior suggestion that fetal station or head position are reasons to select a patient for delayed pushing are not supported by the findings in this recent trial. Together, these data suggest that delayed pushing should not be performed in nulliparous patients with neuraxial anesthesia for the intent to increase their chance of a spontaneous vaginal delivery. For women who are considering delayed pushing, obstetrician-gynecologists and other obstetric providers should inform them of potential risks associated with delayed pushing.