Concerns About Taking Emergency Contraceptive Pills Near Ovulation

Concerns about taking emergency contraception around the time of ovulation?

Hello! My girlfriend got her period on March 1st, and we had unprotected intercourse around March 14th, with ejaculation outside.
She took emergency contraception within two hours afterward, but now it's April 14th and her period still hasn't arrived.
Although we tested for pregnancy last week and it was negative, we're still worried since her period is so late.
I read online that taking emergency contraception after ovulation might not be effective.
What is the doctor's opinion on this? (Feeling anxious)

Mr. Hsu, 20~29 year old female. Ask Date: 2024/04/14

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, the chances of pregnancy should be low.
Please wait another week or two, and if your period still hasn't arrived, I recommend seeing a gynecologist.
Wishing you good health.

Reply Date: 2024/04/14

More Info

When it comes to concerns about taking emergency contraceptive pills (ECPs) near ovulation, it's important to understand how these medications work and the timing of ovulation in relation to the menstrual cycle.
Emergency contraceptive pills, such as levonorgestrel (Plan B) and ulipristal acetate (ella), are designed to prevent pregnancy after unprotected intercourse. They are most effective when taken as soon as possible after the event, ideally within 72 hours for levonorgestrel and up to 120 hours for ulipristal acetate. The primary mechanism of action for these pills is to delay or inhibit ovulation. If ovulation has already occurred, the effectiveness of ECPs diminishes significantly, particularly for levonorgestrel.

In your case, since your girlfriend's last menstrual period started on March 1 and you had unprotected intercourse around March 14, this timing is crucial. Ovulation typically occurs about 14 days before the next expected period, which means it could have occurred around March 15-17 for a typical 28-day cycle. If she took the emergency contraceptive pill within two hours after intercourse, it may have been effective in preventing ovulation, but if ovulation had already occurred, the pill would not prevent pregnancy.

The fact that her period is now late (as of April 14) is understandably concerning. A missed period can be caused by various factors, including stress, hormonal imbalances, or the effects of the emergency contraceptive itself. ECPs can cause temporary changes in the menstrual cycle, leading to delays in the next period.
You mentioned that a pregnancy test was taken last week and it was negative, which is a good sign. However, if her period does not arrive soon, it would be advisable to take another pregnancy test or consult a healthcare provider for further evaluation. Sometimes, a blood test for pregnancy can provide more definitive results than a home urine test.

In summary, while taking emergency contraception close to ovulation can reduce its effectiveness, it does not guarantee pregnancy. The delay in menstruation could be due to the hormonal effects of the ECP or other factors. If the period does not arrive soon, seeking medical advice is the best course of action to rule out pregnancy and discuss any further concerns.
It's also worth noting that if you and your girlfriend are sexually active, discussing regular contraceptive methods with a healthcare provider can help prevent similar situations in the future and provide peace of mind.

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Hello, the chances of pregnancy are low, but it is best to take preventive measures beforehand. Do not rely on the safe period. If your period is more than a week late, it is advisable to see a gynecologist. Wishing you good health.