Medication abortions accounted for 32% of first trimester abortions at Planned Parenthood clinics in the United States in 2008. Considering abortions performed in non-hospital facilities, medication abortions accounted for 24% in 2011 and 31% in 2014. In 2014, facilities that provided a relatively small number of abortions (fewer than 400 procedures per year) were more likely to perform them with medication. Medication abortions accounted for 39% of all U.S. abortions in 2017, and 54% in 2020. Europe
In France, the percentage of medication abortions of all abortions continues to increase: 38% in 2003, 42% in 2004, 44% in 2005, 46% in 2006, 49% in 2007 (vs. 18% in 1996). In England and Wales, 52% of early abortions (less than 9 weeks gestation) in 2009 were medication-based; the percentage of all abortions that are medication-based has increased every year for the past 14 years (from 5% in 1995 to 40% in 2009) and has more than doubled in the last five years. In Scotland, 81.2% of early abortions in 2009 were medication-based (up from 55.8% in 1992 when medication abortion was introduced); the percentage of all abortions that are medication-based has increased every year for the past 17 years (from 16.4% in 1992 to 69.9% in 2009). In Sweden, 85.6% of early abortions and 73.2% of abortions before the end of the 12th week of gestation in 2009 were medication-based; 68.2% of all abortions in 2009 were medication-based. In Great Britain and Sweden, mifepristone is licensed for use with vaginal gemeprost or oral misoprostol.
Mifepristones relative binding affinity at the progesterone receptor is more than twice that of progesterone, its relative binding affinity at the glucocorticoid receptor is more than three times that of dexamethasone and more than ten times that of cortisol. Its relative binding affinity at the androgen receptor is less than one-third that of testosterone, and it does not bind to the estrogen receptor or the mineralocorticoid receptor.Mifepristone as a regular contraceptive at 2 mg daily prevents ovulation (1 mg daily does not). A single preovulatory 10-mg dose of mifepristone delays ovulation by three to four days and is as effective an emergency contraceptive as a single 1.5-mg dose of the progestin levonorgestrel.In women, mifepristone at doses greater or equal to 1 mg/kg antagonizes the endometrial and myometrial effects of progesterone. In humans, an antiglucocorticoid effect of mifepristone is manifested at doses greater or equal to 4.5 mg/kg by a compensatory increase in ACTH and cortisol. In animals, a weak antiandrogenic effect is seen with prolonged administration of very high doses of 10 to 100 mg/kg.In medication abortion regimens, mifepristone blockade of progesterone receptors directly causes endometrial decidual degeneration, cervical softening and dilatation, release of endogenous prostaglandins, and an increase in the sensitivity of the myometrium to the contractile effects of prostaglandins.