1.   How do ECPs work?

ECPs prevent the release of an egg from the ovary or delay its release by 5 to 7 days. By then, any sperm in the woman’s reproductive tract will have died, since sperm can survive there for only about 5 days. If ovulation has occurred and the egg was fertilized, ECPs do not prevent implantation or disrupt an already established pregnancy. 

2.   Do ECPs disrupt an existing pregnancy?

No. ECPs do not work if a woman is already pregnant.

3.   Will ECPs harm the fetus if a woman accidentally takes them while she is pregnant?

No. Evidence does not show that ECPs will cause birth defects or otherwise harm the fetus if a woman is already pregnant when she takes ECPs or if ECPs fail to prevent pregnancy.

4.   How long do ECPs protect a woman from pregnancy?

Women who take ECPs should understand that they could become pregnant the next time they have sex unless they begin to use another method of contraception at once. Because ECPs delay ovulation in some women, she may be most fertile soon after taking ECPs. If she wants ongoing protection from pregnancy, she must start using another contraceptive method by the next day, including a backup method if starting her continuing method requires it. In particular, a woman who has taken UPA-ECPs should wait until the 6th day to start a hormonal contraceptive. She should use a backup method during this period.

5.   Can ECPs be used more than once?

Yes. If needed, ECPs can be taken again, even in the same cycle. A woman who needs ECPs often may want to consider a longer-acting and more effective family planning method.

6.   Should women use ECPs as a continuing method of contraception?

A woman can use ECPs whenever she needs them, even more than once in the same cycle. However, relying on ECPs as an ongoing method should not be advised. It is not certain that ECPs, taken every time after sex, would be as effective as regular, continuing methods of contraception. Also, women who often take ECPs may have more side effects. Repeated use of ECPs poses no known health risks. It may be helpful, however, to screen women who take ECPs often for health conditions that can limit use of hormonal contraceptives.

7.   What oral contraceptive pills can be used as ECPs?

Many combined (estrogen-progestin) oral contraceptives and progestin-only pills can be used as ECPs. Any pills containing the hormones used for emergency contraception—levonorgestrel, norgestrel, norethindrone, and any of these progestins together with estrogen (ethinyl estradiol)—can be used.

8.   Is it safe to take 40 or 50 progestin-only pills as ECPs?

Yes. Progestin-only pills contain very small amounts of hormone. Thus, it is necessary to take many pills in order to receive the total ECP dose needed. In contrast, the ECP dosage with combined (estrogen- progestin) oral contraceptives is generally only 2 to 5 pills in each of 2 doses 12 hours apart. Women should not take 40 or 50 combined (estrogen-progestin) oral contraceptive pills as ECPs.

For women who have been continuing users of POPs, this may be the method of emergency contraception most convenient for her, or the only method available in time.

9.   What is ulipristal acetate (UPA)?

UPA is an anti-progestin—that is, it modifies the activity of the natural hormone progesterone in a woman’s monthly cycle. Thus, like other ECPs, UPA-ECPs probably work by blocking or delaying release of an egg from the ovary (ovulation). All ECPs should be taken as soon as possible for greatest effectiveness. UPA-ECPs may be more effective than other ECPs between 72 hours and 120 hours after unprotected sex. UPA-ECPs have been available in Europe since 2009 and received approval from the United States Food and Drug Administration in 2010 for use as an emergency contraceptive. They are now available in more than 50 countries. UPA-ECPs are not intended for use as a continuing oral contraceptive.

10.  Are ECPs safe for women living with HIV? Can women on antiretroviral therapy safely use ECPs?

Yes. Women living with HIV and those on antiretroviral therapy can safely use ECPs.

11.  Are ECPs appropriate for adolescents?

Yes. A study of ECP use among girls 13 to 16 years old found it safe. Furthermore, all of the study participants were able to use ECPs correctly. Also, access to ECPs does not influence sexual behavior.

Adolescents might particularly need ECPs because of high rates of forced sex, stigma about obtaining contraceptives, limited ability to plan for sex, and errors in using contraceptives.

12.  Can a woman who cannot use combined (estrogen-progestin) oral contraceptives or progestin-only pills as an ongoing method still safely use ECPs?

Yes. This is because ECP treatment is very brief and the dose is small.

13.  If ECPs failed to prevent pregnancy, does a woman have a greater chance of that pregnancy being an ectopic pregnancy?

No evidence suggests that ECPs increase the risk of ectopic pregnancy. Worldwide studies of progestin-only ECPs, including a US Food and Drug Administration review, have not found higher rates of ectopic pregnancy after ECPs failed than are found among pregnancies generally.

14.  Why give women ECPs before they need them? Won’t that discourage or otherwise affect contraceptive use?

No. Studies of women given ECPs in advance report these findings:

  • Women who had ECPs on hand took them sooner after having unprotected sex than women who had to seek out ECPs. Progestin-only ECPs are more likely to be effective when taken sooner.

  • Women given ECPs ahead of time were more likely to use them when needed than women who had to go to a provider to get ECPs.

  • Women continued to use other contraceptive methods as they did before obtaining ECPs in advance.

  • Women did not have unprotected sex more often.

If ECPs require a prescription and cannot be given in advance, give a prescription that can be used as needed.

15.  If a woman buys ECPs over the counter, can she use them correctly?

Yes. Taking ECPs is simple, and medical supervision is not needed. Studies show that both young and adult women find the label and instructions easy to understand. In some countries ECPs are approved for over-the-counter sales or nonprescription use. These countries include Canada, China, India, the United States, and many others around the world.