Pregnancy begins when the fertilized egg is implanted in the woman's uterine wall.
This occurs at the end of the first week after conception. Minipills are oral contraceptive pills containing progestin only, taken within 72 hours after sexual intercourse, followed by a second dose 12 hours later. Because emergency contraception is used at all stages of a woman's menstrual cycle, its mode of action varies. After intercourse, Emergency Contraception may prevent pregnancy by delaying or inhibiting ovulation, inhibiting fertilization, or inhibiting implantation of the fertilized egg. Some extremist groups oppose Emergency Contraception by equating Emergency Contraception with abortion, which they also oppose.