Does Emergency Contraceptive Affect Your Menstrual Cycle?

Menstruation was expected on March 15. If emergency contraception was taken, could it cause an earlier onset?

On February 28, unprotected intercourse occurred.
Since it was about 25 hours before ovulation, I took emergency contraception the next day.
My normal menstrual period is expected on March 15 (it has been regular before).
Will taking emergency contraception affect my menstrual cycle? I used a pregnancy test on March 12 and it showed one line.
Is this result accurate? Thank you.

Niming, 20~29 year old female. Ask Date: 2018/03/13

Dr. Huang Jianzhong reply Obstetrics and Gynecology

On February 28, unprotected intercourse occurred.
Since it was the day before ovulation, the next day, approximately 25 hours later, emergency contraception was taken.
The expected menstrual period should be on March 15 (previous cycles have been regular).

1.
Does taking emergency contraception affect the menstrual cycle?
Answer: Yes, taking emergency contraception can affect the menstrual cycle.
2.
A pregnancy test was taken on March 12, which showed one line.
Is this result accurate?
Answer: It is recommended to take another pregnancy test on March 19 for more accurate results.

Reply Date: 2018/03/13

More Info

Emergency contraceptive pills (ECPs), commonly known as "morning-after pills," can indeed affect your menstrual cycle, but the extent and nature of this effect can vary from person to person. ECPs, such as those containing levonorgestrel or ulipristal acetate, work primarily by delaying ovulation, preventing fertilization, or inhibiting implantation of a fertilized egg.
When you take an emergency contraceptive, it can lead to changes in your menstrual cycle. Some women may experience their next period earlier or later than expected. It is not uncommon for the menstrual cycle to be disrupted after taking ECPs, especially if they are taken close to the time of ovulation. In your case, since you took the emergency contraceptive about 25 hours after unprotected intercourse during your ovulation period, it is possible that the hormonal changes induced by the ECP could alter the timing of your next period.

Typically, if you have a regular menstrual cycle, you might expect your period to arrive around the same time each month. However, after taking ECPs, some women report their period arriving a few days earlier or later than usual. It is also possible for the flow to be lighter or heavier than normal.
Regarding your specific situation, if your expected period was on March 15 and you took the emergency contraceptive on February 29, it is possible that your period could be affected. If your period is delayed, it is advisable to wait a few days past your expected date before taking a pregnancy test for the most accurate result.
As for the pregnancy test you took on March 12, if it showed one line, that typically indicates a negative result, meaning you are not pregnant. However, keep in mind that testing too early can sometimes lead to false negatives, especially if your period is delayed due to the emergency contraceptive. If your period does not arrive within a week of the expected date, it would be prudent to take another pregnancy test or consult with a healthcare provider for further evaluation.

In summary, taking emergency contraception can affect your menstrual cycle, potentially causing your next period to be earlier or later than expected. If you have concerns about your menstrual cycle or the effectiveness of the emergency contraceptive, it is always best to consult with a healthcare professional for personalized advice and guidance.

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