The two most common approaches to second-stage labor are to delay maternal pushing or initiate immediate pushing once complete cervical dilation occurs, but neither is considered to be the gold standard. A study published in JAMA examined whether immediate or delayed pushing results in higher spontaneous vaginal delivery rates and lower rates of maternal and neonatal complications.
The multicenter, randomized clinical trial included 2404 nulliparous pregnant women at or beyond 37 weeks’ gestation who were admitted for spontaneous or induced labor with neuraxial analgesia between May 2014 and December 2017. At complete cervical dilation (10 cm), patients were randomized to immediate pushing or delayed pushing. Women in the immediate pushing group (n=1200) were instructed to initiate pushing at randomization and those randomized to delay pushing were instructed to wait 60 minutes before pushing.
The primary endpoint of the study was spontaneous vaginal delivery that occurred without the use of forceps, vacuum, or cesarean delivery. Secondary endpoints included total duration of labor, duration of active pushing, and rates of postpartum hemorrhage, operative vaginal delivery and cesarean, perineal lacerations, and neonatal morbidity.
Mean time from complete cervical dilation to pushing was 18.9 minutes (SD = 15.1 minutes) in the immediate pushing group and 59.8 minutes (SD = 21.8 minutes) in the delayed pushing group. Women in the immediate pushing group had a significantly shorter mean duration of second-stage labor (102.4 minutes) compared to women in the delayed pushing group (134.2 minutes). However, the immediate pushing group had a significantly longer mean duration of active pushing (83.7 minutes) compared to the mean duration of active minutes in the delayed pushing group (74.5 minutes).
In the two groups, rates of operative vaginal and cesarean delivery were low and did not differ significantly. In the immediate pushing group, the rate of postpartum hemorrhage was much lower than in the delayed pushing group (2.3% vs 4.0%, respectively). Rates of chorioamnionitis during second-stage labor were also significantly lower in women in the immediate pushing group compared to the delayed pushing group (6.7% vs 9.1%, respectively). There was no significant difference between the two groups when comparing rates of endometriosis, neonatal morbidity, or perineal lacerations.
The authors identified a number of strengths and limitations. Among the strengths mentioned was that the multicenter trial is regionally representative of obstetric patients in the United States. Because obstetrical management was at the discretion of the patient’s clinician, the researchers believe the results may be generalizable to broader populations. Limitations included lack of adjustment for multiple comparisons, raising the possibility that some significant differences in the secondary and exploratory outcomes could have occurred by chance. The study could not be blinded, which raised the possibility of bias.
While the authors identified pros and cons of both delivery methods, ultimately for nulliparous women receiving neuraxial anesthesia, the timing of second-stage pushing did not affect the rate of spontaneous vaginal delivery. However, they also noted that observational data in this and previous studies have suggested that every additional hour spent during the second stage of labor after the first hour increases risk for maternal and neonatal morbidity and delayed pushing significantly increased the duration of the second stage.