Emergency Contraception and Ovulation: Key Questions Answered

Contraceptive issues

Hello, doctor.
I have been taking the oral contraceptive pill (Kiryuan) from July until this month.
However, this month I missed two days and took three pills on the third day, which led to ovulation.
Two days ago, after intercourse, I discovered that the condom broke.
I went to see a gynecologist and had an ultrasound that confirmed ovulation (but the exact timing of ovulation could not be determined).
I also took the emergency contraceptive pill (Yunting) within three hours.
I have the following questions:
1.
How long does it typically take for an egg and sperm to combine to form a fertilized egg?
2.
I read online that taking emergency contraception after ovulation will not result in withdrawal bleeding.
Is this true?
3.
If I continue taking the oral contraceptive pill, will it still be effective?
4.
I saw online that if I have been taking the oral contraceptive pill for several months, I do not need to wait until I have taken seven pills to achieve contraceptive effectiveness.
Is this true?
5.
Currently, I am not taking the oral contraceptive pill.
In the past, I would get my period on the third day after finishing 21 pills.
If I stopped taking them two days ago, will I get my period in the next few days?
6.
What is the effectiveness of the emergency contraceptive pill taken within three hours after ovulation? Thank you, doctor.

Lin, 10~19 year old female. Ask Date: 2023/02/12

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello, when you forget to take your birth control pill, you should take it as soon as you remember, and continue taking the next pill at the usual time.
If you miss taking an effective pill for more than 12 hours, in addition to taking the missed pill, it is best to use an additional barrier method of contraception for seven days.
If you miss a pill for more than 24 hours, stop taking the current birth control pills for seven days (including the days you missed), and then continue with the next cycle.
If you miss a pill and do not experience expected withdrawal bleeding during the subsequent pill-taking period, you should consider the possibility of pregnancy.
Emergency contraception primarily works by delaying or inhibiting ovulation to prevent the sperm from meeting the egg, and it may also change the cervical mucus to reduce the likelihood of fertilization.
Sperm can survive in the female body for up to five days, with the highest fertility occurring in the first two days.
After ovulation, the egg can survive for a maximum of 24 hours.
If the medication is taken before ovulation occurs, it can delay the release of the egg, and by that time, the sperm may no longer be viable, thus achieving contraception.
However, if ovulation has already occurred and more than 24 hours have passed, the egg should also be dead, theoretically making the use of emergency contraception irrelevant, but taking it may still yield "effective" results.
If the body signals ovulation (LH surge) just before taking emergency contraception, the medication may be ineffective.
However, in clinical practice, since the timing of ovulation is difficult to confirm, first-generation emergency contraceptive pills contain Levonorgestrel.
Taking the medication within 72 hours after the incident has a success rate of 52–94%, with quicker administration resulting in better efficacy.
Second-generation emergency contraceptive pills contain Ulipristal acetate.
Taking the medication within 120 hours after the incident has a success rate of 98%, with even better results if taken within 72 hours.
In your situation, if your menstrual period is more than a week late, it is advisable to consult a gynecologist for evaluation.
Thank you! Wishing you peace and health.
Dr.
Zhang

Reply Date: 2023/02/12

More Info

When it comes to understanding emergency contraception and ovulation, there are several key aspects to consider, especially in the context of your recent experiences with both regular and emergency contraceptive pills. Let's address your questions one by one.

1. Timeframe for Fertilization: The process of fertilization occurs relatively quickly after ovulation. Once an egg is released from the ovary, it can be fertilized by sperm within 12 to 24 hours. After fertilization, the zygote (fertilized egg) takes about 5 to 6 days to travel down the fallopian tube and implant itself into the uterine lining. Therefore, if you had unprotected intercourse shortly after ovulation, there is a possibility that fertilization could occur.

2. Withdrawal Bleeding After Emergency Contraception: It is true that taking emergency contraception (like the one you mentioned, "韻婷") after ovulation may not lead to withdrawal bleeding, which is often referred to as "decidual bleeding." This is because the primary mechanism of action for emergency contraceptive pills is to delay or inhibit ovulation. If ovulation has already occurred, the effectiveness of the pill in preventing pregnancy diminishes, and you may not experience the typical withdrawal bleeding that occurs with regular contraceptive pills.

3. Effectiveness of Regular Contraceptive Pills: If you continue taking your regular contraceptive pills (like "祈麗安") after missing doses, they can still be effective, but it depends on how many doses were missed and when. If you missed two consecutive pills and took three at once, you may have disrupted your hormonal balance, which could lead to irregularities in your cycle. However, if you resume taking them as directed, they can still provide contraceptive protection, though it may take a few days for their effectiveness to return fully.

4. Timeframe for Effectiveness of Regular Contraceptive Pills: It is generally accepted that if you have been taking your regular contraceptive pills consistently for several months, you may not need to wait for the full seven days after starting a new pack to achieve contraceptive effectiveness. However, this can vary based on the specific pill formulation and individual health factors. Always consult your healthcare provider for personalized advice.

5. Expected Menstrual Cycle After Stopping Pills: If you have been taking your regular contraceptive pills and stop after completing a pack, you can typically expect your withdrawal bleed (similar to a menstrual period) to occur within a few days after the last pill. Since you mentioned stopping the pills a few days ago, it is reasonable to anticipate that your period may arrive soon, although it can vary from person to person.

6. Effectiveness of Emergency Contraception Taken After Ovulation: Taking emergency contraception within three hours of unprotected intercourse after ovulation can still provide some level of protection, but its effectiveness is significantly reduced compared to taking it before ovulation. The sooner you take it after unprotected intercourse, the better the chances of preventing pregnancy, but it is not guaranteed if ovulation has already occurred.

In summary, while emergency contraception can be effective, its efficacy is highest when taken before ovulation. If you have been taking regular contraceptive pills consistently, they can still offer protection, but missing doses can complicate this. If you have concerns about your menstrual cycle or the effectiveness of your contraceptive methods, it is always best to consult with a healthcare professional for tailored advice and guidance.

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