Mifepristone blocks the pregnancy hormone needed for a pregnany to grow, and Misoprostol helps the cervix to relax and the uterus to contract to expel the pregnancy. There are two regimens for the abortion pills, one which combines Mifepristone and Misoprostol, and one that uses Misoprostol only. The combination of Mifepristone and Misoprostol is most effective (95%), but Misoprostol alone (85%) can be used too .
 WHO. Safe abortion: technical and policy guidance for health systems. Second edition. 2012. Retrieved from: https://apps.who.int/iris/bitstream/handle/10665/70914/?sequence=1