How Well Emergency Contraception Works

    * Combined ECPs reduce the risk of pregnancy by 75 percent if started within 72 hours. For example, eight out of 100 women will become pregnant after having unprotected sex once during the second or third week of their cycles. But only two out of 100 will become pregnant after taking ECPs.

    * Progestin-only ECPs reduce the risk of pregnancy by 89 percent if started within 72 hours. Only one woman out of 100 will become pregnant after taking progestin-only ECPs.

    * Emergency IUD insertion reduces the risk of pregnancy by 99.9 percent. Only one out of 1,000 women will become pregnant after emergency IUD insertion.

Timing Is Important

Timing affects how well ECPs work:

    * ECPs work best taken as soon as possible after unprotected intercourse.

    * The closer a woman is to ovulation at the time of unprotected intercourse, the greater her chances of pregnancy.

Emergency contraception is meant for emergencies only. ECPs are not as effective as the correct and consistent use of reversible contraception - the IUD, the Shot, the Pill, the Patch, or the Ring.

ECPs do not continue to prevent pregnancy during the rest of the cycle. Other methods of birth control must be used.

Emergency contraception offers no protection against sexually transmitted infections. You may want to consider testing for sexually transmitted infections if there is a possibility that unprotected sex put you at risk.