A case series detailing the successful reversal of the effects of mifepristone using progesterone.

Background: Some women who take mifepristone, a progesterone receptor antagonist, in order to terminate their pregnancies, change their minds and desire to stop the medical abortion process. There are only two articles in the medical literature documenting the reversal of the effects of mifepristone.

Objective: We present and analyze a series of women who attempted to reverse the effects of mifepristone by taking supplemental progesterone to determine if the reversal of the effects mifepristone with progesterone is possible and safe. Additionally, we compare different progesterone regimens to determine relative efficacies.

Methods: This is an observational case series of 754 patients who decided to attempt to reverse the medical abortion process after taking mifepristone but before taking the second drug in the protocol, misoprostol. We followed the patients, who were given progesterone in an effort to reverse the effects of mifepristone, and conducted statistical analyses to determine the efficacies of different protocols compared to a control mifepristone embryo survival rate, derived from the literature.

Results: Intramuscular progesterone and high dose oral progesterone were the most effective with reversal rates of 64% (P < 0.001) and 68% (P < 0.001), respectively. There was no apparent increased risk of birth defects. Conclusions: The reversal of the effects of mifepristone using progesterone is safe and effective.