for females ages 18 years and up (full criteria)
healthy people welcome
at UC Davis
study started
estimated completion
Mitchell D Creinin, MD (ucdavis)



Double-blind randomized trial to evaluate the potential impact of progesterone treatment on early pregnancies exposed to mifepristone.

Official Title

A Randomized Trial of Mifepristone Antagonization With High-Dose Progesterone to Prevent Medical Abortion


Medical abortion commonly refers to early pregnancy termination (usually before 10 weeks' gestation) performed without primary surgical intervention and resulting from the use of abortion-inducing medications. The use of medications to cause abortion has been around for almost 70 years but the modern era of medical abortion treatment evolved with the development of mifepristone, a progesterone-receptor blocker with an affinity for the receptor greater than progesterone itself.

Medical abortion with mifepristone and misoprostol is highly effective; however, the risk of continuing pregnancy is still present, especially as gestation advances. While most women opt for further treatment in these scenarios, such as surgical aspiration, there are some who decide to continue the pregnancy. Thus, even following treatment, some women do change their mind.

No well-done study has evaluated whether such treatment works. Poorly controlled case series are not evidence and systematic reviews of continuing pregnancy rates after mifepristone/prostaglandin analogue treatment failure do not reflect real life outcomes. This study is also a first step to understanding if large studies evaluating mifepristone antagonization with high-dose progesterone are indicated and if placebo-controlled randomized trials can be successfully completed when evaluating this question.


Pregnancy, Unwanted mifepristone progesterone abortion Mifepristone 200 MG micronized Progesterone


You can join if…

Open to females ages 18 years and up

  1. Pregnant females 18 years and older at enrollment.
  2. Seeking surgical abortion at 44-63 days' gestation on Study day 1.
  3. Have received counseling and signed informed consent per UCD standard procedures for surgical abortion.
  4. Presence of embryonic gestational cardiac activity on transvaginal ultrasonography.
  5. English-speaking
  6. Willing to sign informed consent and follow study protocol.
  7. Willing to experience potential expulsion of the pregnancy with mifepristone treatment.

You CAN'T join if...

  1. Medical contraindications to medical abortion.
  2. Poorly controlled hypertension (systolic BP >160 or diastolic BP >95)
  3. Significant anemia - known recent hemoglobin <9.5 gm/dL
  4. Clinically significant cardiovascular disease (angina, valvular disease, arrhythmia, or congestive heart failure)
  5. Breastfeeding
  6. Coagulopathy or therapeutic coagulation
  7. Ultrasound evidence of molar or ectopic pregnancy
  8. Chronic systemic corticosteroid use
  9. Adrenal disease
  10. Sickle cell anemia with frequent/recent crises
  11. . Glaucoma
  12. IUD in place during conception, even if removed.
  13. Peanut allergy.
  14. Known intolerance of mifepristone or progesterone.
  15. Any other condition, that in the opinion of the clinician, would contraindicate mifepristone, progesterone or medical abortion.


  • University of California, Davis accepting new patients
    Sacramento California 95817 United States
  • Planned Parenthood Mar Monte accepting new patients
    Sacramento California 95816 United States

Lead Scientist

  • Mitchell D Creinin, MD (ucdavis)
    Professor, Obstetrics and Gynecology. Authored (or co-authored) 110 research publications


accepting new patients
Start Date
Completion Date
University of California, Davis
Phase 1/2
Study Type
Last Updated