Women who waited an hour after full cervical dilation to begin pushing out their babies were nearly twice as likely to require a cesarean delivery as women who began pushing in the first 30 minutes, according to an analysis of 21,034 women in 25 hospitals across the United States, published online October 6 and in the November issue of Obstetrics & Gynecology. The women were also more likely to experience a longer second stage of labor, with more active pushing.
“It is notable that in this large cohort, no maternal or neonatal outcomes were improved in association with delayed pushing,” Lynn M. Yee, MD, MPH, from the Departments of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois, and colleagues write. The work stands in contrast to earlier studies that found that delayed pushing leads to a shorter duration of active pushing.
The analysis used data from births between 2008 and 2011 in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Assessment of Perinatal Excellence cohort. The women included in the study were all nulliparous, with singleton, term, vertex babies. Women who have already had babies vaginally are likely to have another vaginal delivery, so the authors decided that nulliparous women were more “clinically relevant.”
Women who were older, privately insured, white, or had diabetes were more likely to have delayed pushing. Speaking on a podcast for the journal, editor-in-chief Nancy Chescheir, MD, noted that it is possible these women had providers such as nurse midwives that preferred lower intervention approaches. The authors were not able to include provider type in their analysis.
Delayed pushing was more likely in women who had epidural or combined spinal-epidural analgesia, in women with larger babies, and in women who began their second stage of labor during daytime hours. The investigators used these factors, along with the center each delivery occurred in, to adjust their analyses.
Cesarean delivery was more common in women who had delayed pushing (11.2% compared with 5.1%; odds ratio [OR], 2.33; 95% confidence interval [CI], 2.07 – 2.63; P < .001), and was still significant (OR, 1.86; 95% CI, 1.63 – 2.12) after adjusting for confounding factors.
Delayed pushing was also associated with increased odds of an operative vaginal delivery (adjusted OR, 1.26; 95% CI, 1.14 – 1.40) and postpartum hemorrhage (adjusted OR, 1.43; 95% CI, 1.05 – 1.95).
Reasons for cesarean and operative vaginal deliveries were also different between the delayed and early pushing groups. For women with delayed pushing, their reason for a cesarean birth was more likely to be dystocia (83.5% compared with 72.9% for early pushing; P < .001), and less likely to be nonreassuring fetal status (9.3% compared with 20.9%; P < .001).
Similarly, in operative vaginal deliveries, women who had delayed pushing were less likely to have nonreassuring fetal status given as the reason for an operative vaginal delivery (29.0% compared with 42.6%; P < .001), but were more likely to have the reason given as failure to descend (17.0% compared with 11.2%; P < .001) or maternal exhaustion (37.5% compared with 29.1%; P < .001).
The authors were not able to include data on fetal position and station, suggesting that delayed pushing could have been more common in women who were not feeling an urge to push because the baby was too high or badly positioned.
Women who experienced delayed pushing had a longer second stage of labor. This includes the delay. The mean and interquartile range were 170 minutes and from 126 to 232 minutes for women with delayed pushing vs 53 and from 30 to 94 for those with early pushing. Active pushing was also longer, with a mean of 80.4 minutes for delayed pushing and 61.7 minutes for early pushing. On average, the second stage was longer by 107.2 minutes and active pushing was longer by 10.4 minutes, after adjustment for potential confounders.
Outcomes for the babies did not vary by pushing status, after adjusting for confounders. There were no significant differences in neonatal intensive care unit admission, low 5-minute Apgar scores, acidotic umbilical artery pH, or shoulder dystocia.
Delayed pushing did not increase the adjusted odds for major perineal lacerations, episiotomy, or maternal intensive care unit admission, although the authors note the number of admissions to maternal intensive care unit was small.
“This is a daily conversation in labor and deliveries,” said Dr Chescheir. “If this paper holds up, it doesn’t look like there’s any benefit for laboring down either for mom or the baby. It makes me a bit worried about routine use of delayed pushing.” She notes that the Maternal-Fetal Medicine Units network is currently conducting a trial of delayed pushing, which may help clarify the findings.