Success of medication abortion with mifepristone followed by two doses of misoprostol in very early pregnancy.

Objectives: To compare medication abortion (MAB) success in very early pregnancy (VEP) with mifepristone followed by either one or two doses of misoprostol.

Study design: We performed a retrospective cohort analysis of VEP MABs from July 1, 2021 to May 31, 2022 treated with mifepristone 200 mg oral followed by a single dose of misoprostol 800 mcg buccal 24 to 48 hours later and MABs from June 21, 2022 to October 31, 2022 treated with mifepristone 200 mg oral followed by two doses of misoprostol 800 mcg buccal spaced 4 hours apart, with first dose taken 24 to 48 hours after mifepristone. Serum BhCG was collected at the time of mifepristone treatment with additional BhCG collected 48 to 72 hours after misoprostol treatment in both groups. Success was defined as a BhCG decline of ≥50%. MAB failure was defined as ongoing, viable pregnancy determined by follow-up ultrasound or procedural intervention with aspiration.

Results: There were 423 patients in the single-dose misoprostol group and 262 patients in the two-dose misoprostol group. There were no significant differences between the two groups in baseline characteristics. In the single-dose group, 372 (87.9%) were treated successfully; in the two-dose group, 224 (85.5%) were treated successfully. There was no significant difference in MAB success between the groups (p = 0.73).

Conclusions: The addition of a second dose of misoprostol does not improve the success of MAB in VEP.

Implications: Additional research is needed to identify interventions to improve the success of MAB in VEP.