1. Not every pregnancy is welcome. World health report;World Health Organization,2005
2. Jones J., Mosher W., Daniels K. Current contraceptive use in the United States, 2006–2010, and changes in patterns of use since 1995. National Health Statistics Reports, Number 60, October 18, 2012; 2012
3. Practice Bulletin: Emergency Contraception number 112;The American College of Obstetricians and Gynecologists;Obstet Gynecol,2010