Hi, I'm Dr. Emily Carter, a board-certified OB/GYN with over 10 years of experience in women's health. I'm happy to answer your questions about emergency contraception, also known as Plan B.

Let's talk about how Plan B, specifically levonorgestrel emergency contraceptive pills (like Plan B One-Step, Take Action, My Way, etc.), works. It's important to understand that Plan B is not the same thing as a medical abortion (like the abortion pill, mifepristone). Plan B will not end a pregnancy that has already implanted.

Plan B works primarily by delaying ovulation. When taken before ovulation, it prevents the release of an egg from the ovary. This means there is no egg present for a sperm to fertilize, therefore preventing pregnancy.

The effectiveness of Plan B decreases over time and the **longer after unprotected sex it is taken, the less effective it will be.** It is most effective when taken within 72 hours (3 days) after unprotected sex, but it can be taken up to 5 days after. However, studies have shown that it becomes significantly less effective after 72 hours. Here's why the timing matters:

* Before ovulation: If taken before ovulation, Plan B effectively delays ovulation, significantly reducing the chance of pregnancy.
* Close to ovulation: If taken close to ovulation, it may still be able to delay ovulation, but its effectiveness decreases.
* After ovulation: If ovulation has already occurred, Plan B is unlikely to prevent pregnancy.

It's also crucial to understand that **Plan B does not offer continuous protection from pregnancy**. It only works for that one instance of unprotected sex. If you have unprotected sex again after taking Plan B, you will need to take another dose for it to be effective.

**Here's what we know about the effectiveness over time:**

* Within 72 hours (3 days): Plan B is up to 89% effective. This means that out of every 100 women who use Plan B within 72 hours of unprotected sex, approximately 11 will become pregnant.
* Between 72 hours and 120 hours (5 days): Effectiveness decreases significantly. While it may still prevent some pregnancies, it is less reliable.

Important Considerations:

* Weight: Studies have shown that Plan B may be less effective in women with a BMI over 30.
* Medications: Some medications, such as certain anticonvulsants and antibiotics, can interfere with the effectiveness of Plan B. It's always a good idea to talk to your doctor or pharmacist about potential interactions with your current medications.

**If you have any questions or concerns about emergency contraception, please don't hesitate to schedule an appointment with your healthcare provider.** They can provide personalized advice based on your individual circumstances.

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If you take it within 72 hours after you've had unprotected sex, Plan B One-Step can reduce the risk of pregnancy by up to 89%. If you take Plan B One-Step within 24 hours, it is about 95% effective. But you should know that Plan B One-Step is not as effective as regular contraception.read more >>