Emergency Contraception: Delayed Periods and Pregnancy Risks

Emergency contraceptive pill

Hello doctor, I had unprotected sexual intercourse with my boyfriend during my safe period on July 12 and July 17.
Half an hour after the first encounter on July 12, I took the emergency contraceptive pill, Ella (Ulipristal Acetate).
On the evening of July 17, we had unprotected intercourse again, and I bought another emergency contraceptive pill, Plan B (Levonorgestrel), the next morning.
My period app indicates that my menstruation was expected around July 18, but I have taken the Plan B pill in the last two days.
Today, July 19, my period has not arrived yet.
Am I already pregnant, or is this just a delayed period?

Niu Niu, 10~19 year old female. Ask Date: 2018/07/19

Dr. Chen Liqin reply Obstetrics and Gynecology

Emergency contraceptive pills cannot guarantee 100% effectiveness in preventing pregnancy and may cause menstrual irregularities.
It is necessary to visit a hospital for further examination to determine the situation.

Reply Date: 2018/07/19

More Info

When it comes to emergency contraception and understanding the implications of delayed periods, it's essential to consider several factors, including the timing of your menstrual cycle, the nature of your sexual activity, and the effects of emergency contraceptive pills (ECPs) like Ella (ulipristal acetate) and Plan B (levonorgestrel).

From your description, you had unprotected intercourse on July 12 and July 17, and you took emergency contraception shortly after each encounter. The first dose was taken 30 minutes after the first sexual encounter, and the second was taken the morning after the second encounter. Both of these actions are crucial in reducing the risk of pregnancy.

Emergency contraceptive pills work primarily by delaying ovulation. If taken before ovulation, they can effectively prevent the egg from being released, thus preventing fertilization. However, if ovulation has already occurred, ECPs may not be effective. The timing of your menstrual cycle is also important; if your cycle is typically around 28 days, and your expected period was around July 18, taking ECPs could potentially cause a delay in your menstrual cycle due to hormonal fluctuations.

It's also worth noting that stress and anxiety about potential pregnancy can further impact your menstrual cycle. The body can react to stress by delaying ovulation or menstruation, which might explain why your period has not arrived as expected.
Given that you took ECPs, it's not uncommon for your period to be delayed. Many women experience changes in their menstrual cycle after taking emergency contraception, including delayed periods, earlier or later onset of menstruation, or changes in flow.
If your period does not arrive within a week of its expected date, it is advisable to take a home pregnancy test. These tests are most accurate when taken after a missed period. If the test is negative and your period still does not come, you may want to consult with a healthcare provider for further evaluation.
In summary, while the risk of pregnancy exists with unprotected intercourse, taking emergency contraception as you did significantly reduces that risk. The delay in your period could be attributed to the hormonal effects of the ECPs, stress, or other factors. If you remain concerned about the possibility of pregnancy or if your period does not arrive soon, seeking medical advice would be a prudent next step.

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