Labor
Poster Session 2
.jpg "Hayley E. Miller, MD photo")
Hayley E. Miller, MD
Stanford University Hospital
San Francisco, CA, United States
Michael T. Jennings, MD
Stanford University Hospital
Palo Alto, CA, United States
Stephanie A. Leonard, PhD (she/her/hers)
Assistant Professor
Stanford University
Palo Alto, CA, United States
Jonathan A. Mayo, MPH
Stanford University
Palo Alto, CA, United States
Deirdre J. Lyell, MD
Professor
Stanford University Medical Center
Palo Alto, CA, United States
Yasser Y. El Sayed, MD
Director, Maternal-Fetal Medicine
Stanford University
Stanford, CA, United States
Paul Blumenthal, MD
Stanford University Hospital
Palo Alto, CA, United States
Kate Shaw, MD, MS
Stanford University Hospital
Palo Alto, CA, United States
Additional options for outpatient cervical preparation prior to term labor induction are needed. Mifepristone decreases induction times by nearly half in the second trimester when used for cervical preparation. We sought to assess uterine and fetal heart tracing (FHT) response to mifepristone in term, inpatient, labor induction.
Study Design: We conducted an exploratory, unmasked, randomized controlled trial that enrolled nulliparas 18 to 45 years old at 37 to 42 weeks’ gestation undergoing induction with a transcervical balloon. Participants were randomized to receive either oral mifepristone 200 mg or oral misoprostol 50 mcg within three hours of balloon placement. Clinicians managed labor and delivery using standard care. We assessed presence of uterine contractions while the balloon was in place, and uterine tachysystole and category II FHT in the 12 hours following study medication and induction duration.
Results: We enrolled and randomized 30 participants between July 2022 and April 2023. Of the participants who received misoprostol, 86% received one dose and 14% received two doses. In the 12 hours after medication administration, participants who received mifepristone had a median number of contraction 38% lower than those who received misoprostol (p < 0.001) and zero incidence of tachysystole versus five among those who received misoprostol (p=0.04). No category II FHT occurred in either group in the first 12 hours after medication administration. Compared to misoprostol, mifepristone had longer median times with a balloon (2.6 hours, p=0.01) and to complete dilation (8 hours, p=0.01), with a similar proportion delivering by 24 hours (p=0.45).
Conclusion:
In this exploratory study, when used with a balloon at term, compared to misoprostol, mifepristone induced fewer median number of contractions and less tachysystole in the 12 hours following administration. Category II FHT did not occur in the 12 hours following medication administration in both groups. These data may help inform future studies on the safety and efficacy of outpatient mifepristone for pre-induction cervical preparation.