Emergency Contraceptive Pills: Effectiveness and Menstrual Delays Explained

Emergency contraceptive pill

Last month, my girlfriend's period started on November 27.
We had sexual intercourse on December 24, and the condom broke after ejaculation, with some semen on the outside of her vagina.
She took emergency contraception within three hours.
I would like to know what the chances of pregnancy are in this situation.
My girlfriend's period is now three days late; could this be due to taking the emergency contraception?

Nìmíng, 10~19 year old female. Ask Date: 2022/12/29

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, it should be the safe period, so pregnancy is unlikely.
Just observe and take care.
Wishing you good health.

Reply Date: 2022/12/29

More Info

Emergency contraceptive pills (ECPs), commonly known as "morning-after pills," are designed to prevent pregnancy after unprotected intercourse or contraceptive failure, such as a broken condom. The effectiveness of ECPs largely depends on how soon they are taken after the incident. When taken within 72 hours (3 days) after unprotected intercourse, ECPs can reduce the risk of pregnancy by 75-89%. There are two main types of ECPs: those containing levonorgestrel (Plan B One-Step) and those containing ulipristal acetate (Ella). Both types work primarily by delaying ovulation, thereby preventing fertilization.

In your case, since your girlfriend took the emergency contraceptive pill within three hours after the condom broke, the chances of pregnancy are significantly reduced. However, it is important to note that while ECPs are effective, they are not 100% guaranteed to prevent pregnancy. Factors such as the timing of ovulation in her menstrual cycle can influence the effectiveness of the pill. If she was close to ovulation when the incident occurred, there might still be a slight risk of pregnancy.

Regarding the delay in her menstrual cycle, it is not uncommon for ECPs to cause changes in menstrual patterns. After taking emergency contraception, some women may experience a delay in their next period, while others may have an earlier onset or a heavier or lighter flow than usual. The hormonal changes induced by the ECP can disrupt the regular menstrual cycle, leading to these variations. In your girlfriend's case, a three-day delay in her period is within the range of expected side effects after taking ECPs.

If her period does not arrive within a week of the expected date, it would be advisable for her to take a pregnancy test to confirm whether or not she is pregnant. Additionally, if she experiences any unusual symptoms, such as severe abdominal pain or heavy bleeding, she should consult a healthcare provider for further evaluation.

In summary, while the risk of pregnancy after taking ECPs shortly after the incident is low, it is not entirely eliminated. The delay in her menstrual cycle could be attributed to the hormonal effects of the emergency contraceptive pill. If her period does not arrive soon, a pregnancy test is recommended to rule out pregnancy. It is also important to have open communication with her healthcare provider regarding any concerns or questions about menstrual irregularities or the use of emergency contraception in the future.

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