USA – Outcomes of abortion after 26 weeks by timing of mifepristone

Contraception June 2024;134(110407)  DOI:

by CN Goldfrab, A Picciotto, J Kuperstock, J Russo, MF Reeves

Center for Science in the Public Interest



The safe and effective use of mifepristone in first- and second-trimester abortion care has been widely documented. Previous literature shows that mifepristone combined with misoprostol for second-trimester induction abortion results in decreased induction times proportional to the length of the mifepristone to misoprostol interval. Mifepristone use in third-trimester abortion is less studied. The DuPont Clinic, an independent all-trimester abortion clinic in Washington, D.C., employs mifepristone for abortion through 31 weeks 6 days, followed by uterine evacuation 1-2 days later, depending on gestational age. We assessed outcomes after 26 weeks by timing of mifepristone administration.


We reviewed charts at the DuPont Clinic from January 2018 through June 2020, recording relevant patient characteristics and clinical data. Our protocol begins with intra-fetal lidocaine injection to induce fetal asystole (cardiac arrest) followed by two- or three-day processes based on factors including prior mode of delivery. Two-day patients receive mifepristone with dilator placement on day one. Three-day patients receive mifepristone after injection; dilators are placed on day two. On procedure day, all patients receive doses of misoprostol until adequate dilation is achieved, followed by instrumented uterine evacuation. Our primary outcome was induction time. We defined mifepristone time as time from mifepristone administration to induction start, and induction time as time from induction start to the end of evacuation procedure. We used linear regression to estimate the impact on induction time of mifepristone time, gestational age, and prior vaginal deliveries. Ethical review was obtained from Stanford University.


We identified 295 patients; 139 (47%), 99 (34%), and 57 (19%) were 26-27, 28-29, and 30-31 weeks gestation (inclusive), respectively, of which 45 (15%) were two-day and 250 (85%) were three-day procedures. Two- and three-day procedure patients had median mifepristone times of 20.8 hours (10-90%ile: 18.7, 39.8) and 41.6 hours (10-90%ile: 37.6, 43.7), respectively. Ten patients (3.4%) had artificial rupture of membranes with dilator placement; twelve (4.1%) had overnight or early morning procedures.

Median induction time for two- and three-day procedure patients was 3.3 hours (10-90%ile: 0.3, 7.8) and 2.7 hours (10-90%ile: 0.5, 6.5), respectively.

Each additional 6-hours of mifepristone was associated with a 37-minute decrease in induction time (95%CI: 18, 55 minutes, p<0.0001). Each week of gestational age was associated with a 20-minute increase in induction time (95%CI: 6, 35 minutes, p=0.006). Each prior vaginal delivery was associated with a 33-minute decrease in induction time (95%CI: 11, 54 minutes, p=0.004). Prior caesarean delivery and patient age were not associated with a significant change in induction time.


Increased mifepristone time was significantly correlated with clinically relevant decreases in induction time. Increases in prior vaginal deliveries were also significantly correlated with shorter induction times, while increasing gestational age was significantly associated with longer induction time. Induction time was not significantly affected by prior caesarean delivery or patient age. Mifepristone administration one to two days prior to procedure is a safe and effective method for abortion after 26 weeks.