Caroline Helwick

February 04, 2016

ATLANTA — For the induction of labor, a combination of methods is more effective than a single method, according to results from the randomized Foley or Misoprostol for the Management of Induction (FOR MOMI) trial.

"There really is not one standard of care at this point. This is the first randomized trial comparing four different methods of induction in one head-to-head trial," said Lisa Levine, MD, from the maternal and child health research program at the University of Pennsylvania in Philadelphia.

"We found that combined methods of induction achieve a faster delivery time than single agents, regardless of parity," Dr Levine reported here at the Society for Maternal-Fetal Medicine 2016 Pregnancy Meeting.

Overall, when misoprostol or cervical Foley were used, time to delivery was nearly 18 hours. However, when methods were combined, time to delivery was 13 to 14 hours.

"My recommendation now is that for women who are accepting of dual agents, the combined method is the induction method of choice and should be recommended to decrease the length of labor," Dr Levine told with Medscape Medical News.

After the exclusion of Cesarean deliveries, the analysis showed that the concurrent use of misoprostol and a cervical Foley catheter was the superior method. Delivery was twice as fast with this combination than with either method alone.

Induction approaches differ regionally and institutionally. Although some physicians sometimes use a combined strategy, they have done so without evidence of the benefit and risks, Dr Levine reported.

 
The most effective method for inducing labor has not been established in the medical literature.
 

"The most effective method for inducing labor has not been established in the medical literature," she said. "This is likely due, in part, to the lack of head-to-head studies comparing multiple induction agents."

The prospective FOR MOMI trial assessed time to delivery with four routinely used methods of induction: misoprostol alone; concurrent misoprostol and cervical Foley catheter; cervical Foley catheter alone; and concurrent oxytocin and cervical Foley catheter.

The investigators hypothesized that time to delivery would be shorter with combined methods than with misoprostol or Foley alone, and that there would be no increase in Cesarean delivery or maternal or neonatal morbidity.

The nulliparous and multiparous women, who were at least 37 weeks pregnant, gave birth at the Hospital of the University of Pennsylvania from May 2013 to June 2015. All women were pregnant with singletons and had intact membranes, a Bishop score of 6 or less, cervical dilation of 2 cm or less, and cephalic presentation.

The study involved 491 women, 78% of whom were black and 65% of whom were publicly insured. Median age was 27 years, body mass index was approximately 29 kg/m², and mean gestational age at induction was approximately 39 weeks. The demographic and clinical characteristics of the women in the four treatment groups were similar.

Each induction method followed a standardized protocol, and standard protocols were followed for amniotomy, active labor, and Cesarean delivery. Briefly, misoprostol 25 µg was administered every 3 hours, oxytocin was started at 2 mU/min and was increased by 2 mU every 15 minutes to a maximum of 40 mU, and an 18F Foley balloon was inflated to 60 cc for cervical Foley placement.

The primary outcome was time to delivery. Secondary outcomes were Cesarean delivery rates, time to vaginal delivery, the rate of delivery within 12 to 24 hours, time to active labor, length of hospital stay for mother and neonate, incidence of chorioamnionitis, and composites of maternal morbidity and neonatal morbidity.

Primary and Secondary Outcomes Met

"We found a significant difference in our primary outcome — time to delivery — among the groups," Dr Levine reported.

When only women who delivered vaginally were considered, time to delivery was still faster with the combinations than with the misoprostol or Foley alone.

Overall, time to vaginal delivery was better with the two combinations than with misoprostol or Foley alone (approximately 11.0 vs 16 hours; P < .001). The same was true for nulliparous women (approximately 15.0 vs 19.0 hours; P < .001).

For multiparous women, time to vaginal delivery was better with the combinations than with either misoprostol or Foley only (approximately 10.0 vs 12.9 vs 14.8 hours; P < .001).

For women who delivered vaginally, time-to-delivery regression analysis, after adjustment for parity, showed that the misoprostol and cervical Foley combination was superior. "When using misoprostol alone or cervical Foley alone as the reference group, combined misoprostol and cervical Foley is the only method that is significantly faster, achieving a delivery that is almost twice as fast (P < .001)," Dr Levine explained.

Table. Time to Delivery by Treatment Group

Women Misoprostol Only, h Misoprostol and Foley, h Foley Only, h Oxytocin and Foley, h P Value
Nulliparous 21.4 16.2 21.0 17.7 <.001
Multiparous 12.9 9.3 15.5 10.4 <.001
All 17.6 13.1 17.7 14.5 <.001

 

The risk for Cesarean delivery was 24.2% with misoprostol alone, 27.6% with misoprostol and cervical Foley catheter, 28.5% with cervical Foley catheter alone, and 30.4% with oxytocin and cervical Foley catheter. The difference among the groups was not significant (P = 0.7).

"We were not powered to say that there was definitely no difference in Cesarean sections, but we did not observe any," Dr Levine pointed out.

Two to three times more women treated with the combinations than with either misoprostol or Foley alone delivered within 12 to 24 hours (P = .001).

Secondary maternal and neonatal outcomes were no worse with the combinations than with misoprostol or Foley alone. Composite maternal morbidity was lower with the combination of misoprostol and cervical Foley than with the other methods (4.1% vs 6.7% - 10.6%), although this difference was not significant.

"After this study, we now use misoprostol and cervical Foley concurrently," Dr Levine told Medscape Medical News.

 
If all these women were treated with combination methods, they would spend at least 3.5 million fewer hours in labor.
 

Dr Levine emphasized the huge clinical impact of incorporating this practice. "More than 20% of women undergo an induction annually, equating to almost 1 million women," she reported. If all these women were treated with combination methods, they would spend at least 3.5 million fewer hours in labor.

This has major implications for the healthcare system, she added. The ability to shorten the length of time that women spend in labor, without increasing rates of Cesarean delivery or maternal and neonatal complications, has obvious clinical and financial implications.

Experts agree on the potential impact of the findings. "This is a very relevant study because it addresses the issue of what is the best method to initiate labor induction, which is a question that occurs on a daily basis at every hospital," said Sean Blackwell, MD, professor and chair of Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School, University of Texas Health Science Center at Houston.

"Studies that answer 'everyday clinical questions' such as these have profound impact," Dr Blackwell said.

These findings are important, "given that over 20% of women undergo induction of labor in the United States," said Uma Reddy, MD, from the Eunice Kennedy Shriver National Institute of Child Health and Human Development in Bethesda, Maryland.

"By using a rigorous study design of randomizing women to the most common induction methods," Dr Levine and her colleagues obtained high-quality data, she explained.

However, Dr Reddy said, a larger study will be needed to understand the impact of various induction regimens on low-frequency but more severe adverse neonatal and maternal outcomes.

Dr Levine, Dr Reddy, and Dr Blackwell have disclosed no relevant financial relationships.

Society for Maternal-Fetal Medicine (SMFM) 2016 Pregnancy Meeting: Abstract 5. Presented February 4, 2016.

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