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The Emergency Contraception Website - Your website for the "Morning After"

Answers to Frequently Asked Questions About...

Risk of Pregnancy

When can I take a pregnancy test and be sure that it is accurate?

If it has been at least 10 days since you had unprotected sex and you have not gotten your period when you think you should have, you can take a home pregnancy test to find out if you are pregnant. Before that, a negative test result won’t be accurate, and you definitely can’t tell if you’re going to get pregnant in the first few days after sex - the time when you would be taking emergency contraceptive pills (sometimes called "morning after pills" or "day after pills"). If the test is negative but you are still worried, you can take a second home pregnancy test in another week. If the result is positive, you should contact your health care provider to discuss your options, including prenatal care or abortion.

If you think you might already be pregnant because your period is late, you can take a home pregnancy test before using emergency contraception - although it’s not necessary from a medical standpoint. Emergency contraceptive pills won’t work if you are already pregnant, and they will not harm you or your fetus (although evidence for ella is still limited).

Remember, emergency contraception significantly reduces the chances that you will become pregnant if you had sex and your birth control failed, you didn’t use contraception, or you were forced to have sex. If you have had sex and think that you might be at risk of pregnancy, take action right away to find out what your options are for emergency contraception. Clinical studies show that ella is effective for 5 days after unprotected sex, and that progestin-only pills (like Plan B One-Step or Next Choice One Dose) work up to 4 days after. However, what's important for each individual woman is where is you are in your menstrual cycle (how close you are to ovulation). If you are close to ovulation, EC may not be able to prevent pregnancy if you wait 5 days. Therefore, the best thing to do is take EC as soon as you can get it. A thorough and up-to-date academic review of the medical and social science literature on emergency contraception is available here .


This website is operated by the Office of Population Research at Princeton University and has no connection with any pharmaceutical company or for-profit organization.

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