Emergency Contraception: Effectiveness and Timing After Unprotected Intercourse

Emergency contraceptive pill

Hello, Doctor.
I had my menstrual period starting on October 31 (lasting for 7 days, with a cycle of approximately 24-27 days, but usually arriving 3-4 days early each month).
My last period was on October 4.
On November 14, I did not pay attention to my ovulation period and did not use a condom, but I practiced withdrawal.
I took emergency contraception within 5 hours as instructed by the pharmacist, which included taking a coated tablet and one bottle of liquid medication, and then I took another bottle of liquid medication the next morning.
Can you tell me if this will be effective for contraception? When should I expect my next period? Will taking traditional Chinese medicine affect the effectiveness of the emergency contraception?

Ling, 20~29 year old female. Ask Date: 2020/11/19

Dr. Huang Zifei reply Obstetrics and Gynecology

Dear Ling,
Basically, taking emergency contraception within 24 hours can achieve a 95% effectiveness in preventing pregnancy.
However, the high concentration of hormones in emergency contraceptive pills may affect your menstrual cycle, potentially causing it to arrive earlier.
Traditional Chinese medicine may also influence the effectiveness of contraception.
If your period is delayed for more than a week, remember to take a pregnancy test.
For any other concerns, it is advisable to consult a gynecologist.
Dr.
Huang Zifei, Department of Obstetrics and Gynecology, Nantou Hospital

Reply Date: 2020/11/19

More Info

Emergency contraception (EC) is a critical option for preventing unintended pregnancies after unprotected intercourse. The effectiveness of emergency contraceptive pills (ECPs) like levonorgestrel (often referred to as Plan B) or ulipristal acetate (ella) depends significantly on the timing of administration relative to ovulation.

In your case, you mentioned that your last menstrual period started on October 31 and that you had unprotected intercourse on November 14, which you believe was around your ovulation period. It’s important to note that sperm can survive in the female reproductive tract for up to five days, and if ovulation occurs shortly after intercourse, there is a risk of fertilization.

You took the emergency contraceptive pill within five hours of intercourse, which is excellent timing. ECPs are most effective when taken as soon as possible after unprotected sex, ideally within 72 hours for levonorgestrel and up to 120 hours for ulipristal acetate. Since you took the medication promptly, you have maximized your chances of preventing pregnancy.

Regarding your menstrual cycle, if your cycle typically ranges from 24 to 27 days and you usually experience your period a few days earlier than expected, you can anticipate your next period around November 28 to December 1. However, it’s important to remember that taking emergency contraception can sometimes cause changes in your menstrual cycle, including earlier or later onset of your next period, as well as variations in flow and duration.

As for the use of traditional Chinese medicine (TCM) or any herbal supplements, it’s crucial to be cautious. While there is limited research on the interactions between TCM and emergency contraceptive pills, some herbal remedies can potentially affect hormonal balance or liver metabolism, which may influence the effectiveness of hormonal contraceptives. If you are taking any herbal supplements, it’s advisable to consult with a healthcare provider to ensure they do not interfere with the efficacy of the emergency contraception.

In summary, based on the timing of your emergency contraception and your menstrual cycle history, you have taken the right steps to reduce the risk of unintended pregnancy. Keep an eye on your menstrual cycle, and if your period is significantly delayed (more than a week), consider taking a pregnancy test. If you have further concerns or experience unusual symptoms, it’s always best to consult with a healthcare professional for personalized advice and support.

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