Can Emergency Contraceptive Pills Affect a Developing Embryo?

Pregnant after taking emergency contraception?

Hello doctor, I would like to ask, I had intercourse with my husband on September 11 and took the emergency contraceptive pill on September 12.
We had intercourse again on September 15, and I tested positive for pregnancy on September 27.
Will this have any negative effects on the embryo?

lin, 30~39 year old female. Ask Date: 2015/09/27

Dr. Xu Junrui reply Obstetrics and Gynecology

Generally speaking, a newly fertilized embryo is not affected by teratogenic drugs within the first 14 days.
Therefore, in your case, there should be no impact.
However, it is still advisable to see a physician as soon as possible to confirm your exact gestational age for safety.

Reply Date: 2015/09/27

More Info

Emergency Contraceptive Pills (ECPs), commonly known as "morning-after pills," are designed to prevent pregnancy after unprotected intercourse or contraceptive failure. The primary active ingredients in these pills are levonorgestrel or ulipristal acetate, which work mainly by delaying ovulation, preventing fertilization, or inhibiting implantation of a fertilized egg.
In your case, since you took the emergency contraceptive pill shortly after unprotected intercourse on September 12, it is important to understand how these medications function and their potential effects on a developing embryo. Research indicates that ECPs are most effective when taken as soon as possible after unprotected sex, ideally within 72 hours, but they can be taken up to five days after intercourse, depending on the type of pill used.
Regarding your concern about the potential impact of ECPs on a developing embryo, studies have shown that if fertilization has already occurred, ECPs do not have an abortive effect. This means that if you were already pregnant at the time of taking the ECP, it would not disrupt an established pregnancy. The mechanism of action of ECPs does not include terminating an existing pregnancy; rather, they primarily work to prevent ovulation and fertilization.

Since you mentioned that you had intercourse again on September 15 and subsequently tested positive for pregnancy on September 27, it is likely that the pregnancy occurred after the use of the ECP, assuming you were not already pregnant at the time of taking the pill. If fertilization occurred after taking the ECP, the medication would not affect the embryo.

As for the safety of ECPs during early pregnancy, current evidence suggests that they do not pose a risk of teratogenic effects (causing malformations) to a developing embryo. The World Health Organization (WHO) and other health authorities have stated that ECPs are safe to use and do not have harmful effects on an ongoing pregnancy.

However, it is always advisable to consult with a healthcare provider regarding any concerns about medications taken during early pregnancy. They can provide personalized advice and reassurance based on your specific situation. If you have any further questions or concerns about your pregnancy or the use of ECPs, please reach out to your healthcare provider for guidance.

In summary, taking emergency contraceptive pills shortly after unprotected intercourse is unlikely to negatively affect a developing embryo if pregnancy has already occurred. The primary function of these pills is to prevent pregnancy, and they do not terminate an existing pregnancy. If you have any lingering concerns, please consult with your healthcare provider for further evaluation and support.

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