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Labor induction at 39 weeks reduced cesarean rate for low-risk, first-time mothers

 

Key clinical point: Women who underwent induced labor experience a significantly lower rate of cesarean delivery, compared with women who received expectant management.

Major finding: 18.6% of women in the induced labor group underwent cesarean delivery, compared with 22.2% in the expectant management group.

Study details: A multicenter randomized, controlled, parallel-group, unmasked trial of 6,106 women from 41 maternal-fetal medicine departments in hospitals participating in the Eunice Kennedy Shriver National Institute of Child Health and Human Development network screened between March 2014 and August 2017.

Disclosures: This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Dr. Silver reports receiving personal fees from Gestavision. The other authors report no relevant financial disclosures..

Source: Grobman WA et al. N Engl J Med. 2018 Aug 9. doi: 10.1056/NEJMoa1800566.

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Induction at 39 weeks is ‘a reasonable choice’

Of the more than 50,000 women screened for the study by Grobman et al., there were more than 44,000 women excluded and more than 16,000 did not participate in the trial. Further, the study participants tended to be younger and comprised more black or Hispanic women than the general population of mothers in the United States, Michael F. Greene, MD, said in a related editorial.

“Readers can only speculate as to why so many women declined to participate in the trial and what implications the demographics of the participants may have for the generalizability of the trial results and the acceptability of elective induction of labor at 39 weeks among women in the United States more generally,” Dr. Greene said. “If induction at 39 weeks becomes a widely popular option, busy obstetrical centers will need to find new ways to accommodate larger numbers of women with longer lengths of stay in the labor and delivery unit.”

Nevertheless, the study reflects a “public preference for a less interventionist approach” to delivery, Dr. Greene said, and the interest is backed by available data. He cited a meta-analysis of 20 randomized trials that found inducing labor at 39 weeks may reduce perinatal morality while not increasing the risk of operative deliveries. Specifically, he noted a randomized trial from the United Kingdom found induction of labor among 619 women at 39 weeks who were at least 35 years old did not affect the participants’ perception of delivery or increase the number of operative deliveries.

“These results across multiple obstetrical centers in the United States, however, should reassure women that elective induction of labor at 39 weeks is a reasonable choice that is very unlikely to result in poorer obstetrical outcomes,” he said.

Dr. Greene is chief of obstetrics and gynecology at Massachusetts General Hospital in Boston. He reported no relevant conflicts of interest. These comments summarize his editorial accompanying the article by Dr. Grobman and his associates ( N Engl J Med. 2018 Aug 9;379[6]:580-1 ).


 

FROM NEW ENGLAND JOURNAL OF MEDICINE

Nulliparous women who were induced at 39 weeks had the same relative risk of adverse perinatal outcomes but a lower risk of a cesarean delivery, compared with women who received expectant management, results that researchers say contrast traditional recommendations for perinatal care, according to study from the New England Journal of Medicine.

Dr. William A. Grobman, professor of obstetrics and gynecology at Northwestern University, Chicago Michele G. Sullivan/Frontline Medical News

Dr. William A. Grobman

“These findings contradict the conclusions of multiple observational studies that have suggested that labor induction is associated with an increased risk of adverse maternal and perinatal outcomes,” William A. Grobman, MD, the Arthur Hale Curtis, MD, Professor of Obstetrics and Gynecology at Northwestern University in Chicago, and his colleagues wrote. “These studies, however, compared women who underwent labor induction with those who had spontaneous labor, which is not a comparison that is useful to guide clinical decision making.”

Dr. Grobman and his colleagues evaluated the deliveries of 3,062 women who underwent labor induction between 39 weeks of gestation and 39 weeks and 4 days of gestation, and compared them with outcomes of 3,044 women who received expectant management until 40 weeks and 5 days of gestation. Women in both groups had a singleton fetus, no indication of early delivery, and did not plan on delivering by C-section. The participants were assessed again at about 38 weeks of gestation and randomly assigned to receive labor induction or expectant management as part of a multicenter randomized, controlled, parallel-group, unmasked trial in 41 maternal-fetal medicine departments in hospitals participating in the Eunice Kennedy Shriver National Institute of Child Health and Human Development network screened between March 2014, and August 2017.

Primary perinatal outcomes and components were defined as perinatal death, respiratory support, an Apgar score of 3 or less at 5 minutes, hypoxic-ischemic encephalopathy, seizure, infection, meconium aspiration syndrome, birth trauma, intracranial or subgaleal hemorrhage, or hypotension that requires vasopressor support. The principal secondary outcome was cesarean delivery, but other secondary outcomes included neonatal or intensive care, infection, postpartum hospital stay, and hypertension, among others.

Dr. Grobman and his colleagues found 132 (4.3%) of neonates in the induction group and 164 (5.4%) in the expectant-management group experienced a primary composite outcome (relative risk, 0.80; 95% confidence interval, 0.64-1.00; P = .049).

Regarding secondary outcomes, there was a significantly lower risk of cesarean delivery in the induction group, with 18.6% of women undergoing a cesarean delivery, compared with 22.2% of women in the expectant-management group (RR, 0.84; 95% CI, 0.76-0.93; P less than .001). Women in the labor induction group had a significantly lower relative risk of hypertensive disorders of pregnancy (9.1%), compared with the expectant-management (14.1%) group (RR, 0.64; 95% CI, 0.56-0.74; P less than .001). The investigators said women who underwent induced labor had lower 10-point Likert scale scores, were more likely to have “extensions of the uterine incision during cesarean delivery,” perceived they had “more control” during delivery, and had a shorter postpartum stay in the hospital, compared with women who received expectant management. However, women in the induced labor group also had a longer stay in the labor and delivery units, they said.

The researchers noted the limitations in this study, which included its unmasked design, lack of power to detect infrequent outcome differences, and the lack of information surrounding labor induction at 39 weeks in low-risk nulliparous women.

“These results suggest that policies aimed at the avoidance of elective labor induction among low-risk nulliparous women at 39 weeks of gestation are unlikely to reduce the rate of cesarean delivery on a population level; the trial provides information that can be incorporated into discussions that rely on principles of shared decision making,” Dr. Grobman and his colleagues wrote.

This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Dr. Silver reports receiving personal fees from Gestavision. The other authors report no relevant financial disclosures.

SOURCE: Grobman WA et al. N Engl J Med. 2018 Aug 9. doi: 10.1056/NEJMoa1800566.

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