Induction of Labor Using a Foley Catheter or Misoprostol: A Systematic Review and Meta-analysis
Authors: ten Eikelder Mieke L. G. , Mast Kelly , van der Velden Annemarie , Bloemenkamp Kitty W. M. , Mol Ben W. 
Published: October 2016

Importance
Induction of labor is a widely used obstetric intervention, occurring in one in four pregnancies. When the cervix is unfavorable, still many different induction methods are used.

Objective
We compared Foley catheter alone to different misoprostol dosages and administration routes, and the combination of Foley catheter with misoprostol.

Evidence acquisition
We reviewed the literature on the best induction method regarding their safety and effectiveness, using the outcome measures hyperstimulation, fetal distress, neonatal morbidity and mortality as well as cesarean delivery, vaginal instrumental delivery, and maternal morbidity. We searched Pubmed, Cochrane, and Web of Science from January 1, 1980 to February 12, 2016. Twenty-two randomized controlled trials (RCTs) were included, comparing Foley catheter with or without misoprostol to misoprostol alone (both vaginal and oral) for induction of labor (5,015 women).

Results
Most included studies were underpowered to detect differences in safety outcomes, as the majority are powered for time to delivery or cesarean delivery. Meta-analysis of these studies does not allow assessment of the safety profile of Foley catheter compared to misoprostol (any dose, any administration route) with sufficient power. For the safety outcomes of the total group of Foley catheter versus misoprostol (any dose, any administration route) (17 studies, 4,234 women) we found that Foley catheter results in less hyperstimulation compared to misoprostol (2% versus 4%; risk ratio [RR], 0.54; 95% confidence interval [CI], 0.37–0.79) and fewer cesarean deliveries for nonreassuring fetal heart rate, 5% vs 7%; RR, 0.72; 95% CI, 0.55–0.95; while there were no statistically significant differences in neonatal outcomes. The total number of cesarean deliveries was 26% versus 22% (RR, 1.16; 95% CI, 1.00–1.34). There were fewer vaginal instrumental deliveries with a Foley catheter compared to misoprostol (10% vs 14%; RR, 0.74; 95% CI, 0.60–0.91). Foley catheter with misoprostol compared to misoprostol alone (any dose, any administration route) (7 studies, 1,073 women) resulted in less hyperstimulation than misoprostol alone (17% vs 23%; RR, 0.71; 95% CI, 0.52–0.97). Cesarean deliveries for nonreassuring fetal heart rate were comparable (7% vs 9%; RR, 0.79; 95% CI, 0.51–1.22). Neonatal outcomes were infrequently reported. The total number of cesarean deliveries was 34% versus 34% (RR, 1.01; 95% CI, 0.86–1.19).

Conclusion
In women with an unripe cervix at term, Foley catheter seems to have a better safety profile than misoprostol (any dose, any administration route) for induction of labor. Larger studies are needed to investigate the safety profile of a Foley catheter compared to separate dosing and administration regimens of misoprostol.

Target Audience
Obstetricians and gynecologists, family physicians.

Learning Objectives
After completing this activity, the learner should be better able to: criticize the used primary outcome measures in many articles on induction of labor and thereby understand that a save delivery is more important than a fast one; appraise articles on induction of labor and understand that most studies are underpowered for important safety outcomes; select the safest induction method; and choose an induction method based on both safety and effectiveness outcomes.