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Once-weekly 50 mg mifepristone as a non-hormonal contraceptive

Prospective Phase III Multi-center Open-label Study of the Efficacy, Safety, and Acceptability of Mifepristone 50 mg Once-weekly as a Contraceptive

Phase 3 Interventional Leiden University Medical Center · NCT06394999

This will test whether taking one 50 mg mifepristone tablet once a week prevents pregnancy in people aged 18–35 who want a non-hormonal, once-weekly oral contraceptive.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment1186 (estimated)
Ages18 Years to 35 Years
SexFemale
SponsorLeiden University Medical Center Academic / other
Locations14 sites (Alkmaar and 13 other locations)
Trial IDNCT06394999 on ClinicalTrials.gov

What this trial studies

In this Phase 3 trial participants will take 50 mg mifepristone once weekly for 12 months as their only method of contraception. The study will record pregnancies, adverse events, menstrual changes, and user acceptability using scheduled clinic visits, daily electronic diaries, and five online questionnaires. Eligible participants are adults 18–35 with BMI under 35 who are sexually active with a non-sterilized partner at least once a month and able to attend visits and complete study reporting. The main goals are to measure pregnancy rates, safety/tolerability, and whether a once-weekly pill is acceptable to users over one year.

Who should consider this trial

Good fit: People aged 18–35 with BMI <35 who are sexually active with a non-sterilized partner at least monthly, willing to use weekly mifepristone as their only contraception for 12 months and to complete electronic diaries and scheduled visits.

Not a fit: People with contraindications to mifepristone, those older than 35 or with BMI ≥35, those unwilling to use mifepristone as their sole contraceptive or unable to complete study visits and daily reporting, or those with sterilized partners are unlikely to benefit from or be eligible for this protocol.

Why it matters

Potential benefit: If successful, this could provide a safe, effective non-hormonal weekly oral contraceptive with fewer hormone-related side effects.

How similar studies have performed: Mifepristone is an established emergency contraceptive and early-phase studies of weekly dosing show promising efficacy and tolerability, but large Phase 3 evidence is still limited.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

1. Age 18-35 at the moment of signing the informed consent.
2. In case of 30 years or older, prior HPV or pap-test.
3. Understand and speak Dutch or English.
4. Willing to use mifepristone as the only method of contraception for 12 months.
5. Able to take oral medication and willing to adhere to the study protocol.
6. Have unprotected vaginal heterosexual intercourse with a non-sterilized partner at least once a month.
7. BMI \< 35 kg/m2.
8. Willing to fill in a daily diary on the smartphone or computer and five times an on-line questionnaire.
9. Able to participate in the scheduled visits and comply with the study protocol.
10. Provide informed consent about participating in study and provide permission to request medical data in the event of complications or pregnancy.
11. In case of not using hormonal contraceptives, menstrual cycle of 21-35 days.
12. In case of Depo-Provera (3 month injectable) at least 3 cycles of 21-35 days after stop.
13. In case of necessary progesterone treatment, be willing to use condoms temporarily.

Exclusion Criteria:

1. Currently pregnant or breast-feeding.
2. Desire to become pregnant within the following 12 months.
3. Signs of current endometritis, incomplete abortion after miscarriage or induced abortion, or retained pla-cental rests after delivery.
4. Undiagnosed post-coital bleeding or unscheduled bleeding (spotting with COC, patch, vaginal ring, hormo-nal IUD, implant allowed).
5. Known subfertility or history of ectopic pregnancy, unless intra-uterine pregnancy afterwards, or grade 3-4 endometriosis proven by laparoscopy.
6. History of gastric reduction or gastric bypass or use of weight-loss medicines.
7. Previous or current liver illness, previous or current infection affecting the liver (such as Hepatitis) or mod-erately abnormal liver enzymes at screening (ALAT, ASAT or bilirubin \> 2 ULN).
8. Current or previous cancer or DCIS.
9. Family history of endometrial cancer, except BRCA genome mutation.
10. Known allergy to mifepristone.
11. Using non-dermal corticosteroids or any drugs that may interact with mifepristone. These include hydan-toins (e.g. phenytoin), barbiturates (e.g. phenobarbital), primidone, carbamazepine, rifampicin, oxcarbaze-pine, topiramate, rifabutin, felbamate, ritonavir, nelfinavir, griseofulvin and products containing St. John's wort (Hypericum perforatum).
12. Treatment with another investigational drug or participating in another intervention study, unless the prin-cipal investigators agree.
13. Undiagnosed reason for severe anemia or increased creatinine.
14. Abnormal previous PAP smear \> pap II without colposcopic evaluation or untreated HSIL.
15. Systolic blood pressure ≥ 180 mmHg and/or diastolic ≥ 110 mmHg (hypertension with medical treatment allowed).
16. Intracavitary abnormalities on vaginal ultrasound, including intracavitary polyps or myomas, endometrium \> 15 mm, or an obvious sign of hydrosalpinx.
17. Previous participation in the WOMEN\&More trial.

Where this trial is running

Alkmaar and 13 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Female ContraceptionOralWeeklyNon-hormonal
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.