Marketed as more private and less invasive than surgical abortion, the drug duo mifepristone (RU-486) and misoprostol work in tandem to shed a women’s uterine lining and induce labor, killing the baby.

Restrictions on the drugs have kept their use lower in the United States than in Western European countries, where they often account for the majority of abortions. But the self-administered abortion drugs now rival surgical abortions in this country, partly due to loosening restrictions.

At Planned Parenthood alone, medication abortion comprised 43 percent of all abortions in 2014, up from 35 percent in 2010. Those numbers soared this year after the Food and Drug Administration eased regulation of the drugs in March to allow ...