Mifepristone works by blocking a hormone that is needed during pregnancy, causing further development to stop. A follow-up pill called misoprostol is then used two days later, which causes the contractions by which the body goes into labor, expelling the fetus. To be effective the procedure must be done within the first 63 days. | Mifepristone works by blocking a hormone that is needed during pregnancy, causing further development to stop. A follow-up pill called misoprostol is then used two days later, which causes the contractions by which the body goes into labor, expelling the fetus. To be effective the procedure must be done within the first 63 days. |