Randomised, double-blind, placebo-controlled, parallel-group clinical trial to evaluate the efficacy of two regimens of ulipristal acetate in combination with misoprostol for medication abortion in women up to 63 days of gestation
Termination of pregnancy (medication abortion) in women up to 63 days of gestation; unintended pregnancy
Intervention group (60 mg): Ulipristal acetate 60 mg orally (two 30 mg tablets) administered under direct supervision in clinic, followed 24 hours later by self-administered buccal misoprostol 800 mcg at home. Comparator group (30 mg): Ulipristal acetate 30 mg orally (one 30 mg tablet + two placebo tablets) administered under direct supervision in clinic, followed 24 hours later by self-administered buccal misoprostol 800 mcg at home. Placebo tablets are used to ensure identical appearance of study packages and maintain double blinding. Randomisation was performed using Stata 18 SE (StataCorp. 2023). A block randomisation scheme with a fixed block size of four was generated separately for each study site. The random number generator was initialised with a fixed seed (20250816) to ensure reproducibility. If enrolment exceeds initial projections at a site, the sequence can be extended by rerunning the program with an updated sample size; in such cases, all prior allocations remain identical to the original scheme, and new allocations are generated in continuation of the same random sequence. The random allocation lists will be used to prepare sequentially numbered, opaque envelopes containing the study medications. Participants will be enrolled sequentially and assigned the next available envelope corresponding to their site.
1. Women aged ≥18 years (or emancipated minors) 2. Intrauterine pregnancy confirmed by ultrasound 3. Gestational age ≤63 days by ultrasound 4. Eligible for medication abortion under standard clinical criteria 5. Resident in Mexico City 6. Access to a telephone for follow-up 7. Able and willing to provide written informed consent
1. Liver or renal disease 2. Confirmed or suspected ectopic pregnancy, gestational trophoblastic disease, or undiagnosed adnexal mass 3. Intrauterine device (IUD) in situ 4. Known allergy to ulipristal acetate, misoprostol, or other prostaglandins 5. Unwilling or unable to attend follow-up visit 6. Unable to provide informed consent