Answers to Frequently Asked Questions About...
Risk of Pregnancy
What is my risk of getting pregnant if I have sex without using contraception or my birth control fails?
Almost any time you have sex without using birth control effectively, there’s a chance you might get pregnant – and using emergency contraceptive pills (also called "morning after pills" or "day after pills") can significantly reduce your risk. Your chances of getting pregnant if you have unprotected sex and don’t use emergency contraception afterwards vary, depending on where you are in your monthly cycle. Researchers have calculated the average risk at different times in a woman’s monthly cycle, but it’s important to remember that your risk could be higher or lower. The risk is highest on the days right before you ovulate (when your ovaries release the egg), reaching a maximum of nearly 30%. You can’t know for sure when you will ovulate, so researchers have calculated the average risk of pregnancy based on a woman’s monthly cycle (since you can figure out when you started your last period).
During the first two days of a woman’s cycle (day 1 being your first day of bleeding), the average risk of pregnancy is virtually zero. After the first two days, the risk starts to rise steadily, reaching 9% on or about day 13. Then it begins to decline slowly until it levels off at about 1% on day 25. It stays at about 1% for the rest of your cycle. (The average monthly cycle lasts 29 days, but it is perfectly normal to have a cycle that lasts as little as 20 days or less or as long as 40 days or more.)
Emergency contraception works before ovulation, but does not appear to work after ovulation has already occurred. ella works closer to the time of ovulation than progestin-only pills, like Plan B One-Step or Next Choice One Dose. Therefore, if you believe that you have had unprotected sex close to the time of ovulation, it might be best to use ella if possible. But it can take time to get a prescription and fill it - the most important thing is to take action as soon as possible after unprotected sex.
If you've had unprotected sex and are wondering if you at risk of pregnancy, this tool from Planned Parenthood can help.
A thorough and up-to-date academic review of the medical and social science literature on emergency contraception, including how it reduces the risk of pregnancy after sex, is available here .