Emergency Contraceptive Pills and Their Effects on Menstrual Cycle

Emergency contraceptive pill, withdrawal method without a condom?

Hello, doctor.
I would like to ask about the issue of pre-exposure prophylaxis: I took the medication for the first time on December 1, during the fifth day of my menstrual period, and I took it consistently every day.
I experienced some light bleeding in between.
After completing 21 days, I stopped the medication for 7 days, and my period only lasted for three days with significantly reduced flow.
On the 8th day (December 29), I started the second pack.
I had unprotected intercourse on January 1 and January 2, but there was external ejaculation.
(1) Is it normal for my period to only last three days with a lighter flow? (2) Is there a possibility of pregnancy from the aforementioned unprotected intercourse? Should I take a pregnancy test?

Miss Lin, 10~19 year old female. Ask Date: 2022/01/14

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello,
The contraceptive pill has the effect of suppressing endometrial hyperplasia (making it more difficult for a fertilized egg to implant).
As the source of menstrual flow decreases, the menstrual volume naturally reduces, rather than being retained in the body.
Combined oral contraceptives (COCs) must be taken at the same time every day; when taken correctly, they can achieve a 99% effectiveness rate in preventing pregnancy.
Thank you! Wishing you peace and health.
Dr.
Zhang

Reply Date: 2022/01/14

More Info

Emergency contraceptive pills (ECPs) are a form of birth control used to prevent pregnancy after unprotected intercourse or contraceptive failure. Understanding their effects on the menstrual cycle is crucial for users to manage their reproductive health effectively.

1. Effects on Menstrual Cycle: It is not uncommon for ECPs to cause changes in menstrual bleeding patterns. When you take ECPs, especially if they contain hormones like levonorgestrel or ulipristal acetate, they can alter the timing and flow of your menstrual cycle. In your case, experiencing a shorter menstrual period with lighter flow after taking the ECPs is within the realm of normal side effects. Hormonal fluctuations caused by the pills can lead to breakthrough bleeding or changes in the regularity and heaviness of menstrual cycles.
The fact that your period lasted only three days and was lighter than usual can be attributed to the hormonal influence of the ECPs. Many users report similar experiences, and while it can be concerning, it typically resolves in subsequent cycles. However, if you notice persistent irregularities or if your next period is significantly delayed, it would be advisable to consult a healthcare provider.

2. Risk of Pregnancy: Regarding the unprotected sexual intercourse you mentioned on January 1 and 2, it is essential to understand that while ECPs are effective, they are not 100% guaranteed to prevent pregnancy. The effectiveness of ECPs is highest when taken as soon as possible after unprotected intercourse, ideally within 72 hours for levonorgestrel and up to 120 hours for ulipristal acetate. Since you were taking the ECPs as prescribed, the risk of pregnancy from the intercourse, especially with the withdrawal method (pulling out), is relatively low, but not zero.

If you are concerned about the possibility of pregnancy, taking a home pregnancy test is a reasonable next step. Most tests are accurate if taken at least one week after the expected date of your period. If your period does not arrive within a week of when it is due, or if you have any symptoms of pregnancy (such as nausea, breast tenderness, or fatigue), you should definitely take a pregnancy test and consult a healthcare provider for further guidance.

In summary, the changes in your menstrual cycle after taking ECPs can be considered normal, and while the risk of pregnancy from the described sexual activity is low, it is not entirely absent. Monitoring your cycle and being aware of your body’s responses to hormonal contraceptives is essential for managing your reproductive health effectively. If you have further concerns or experience significant changes, do not hesitate to reach out to a healthcare professional for personalized advice.

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