Effectiveness of Taking Emergency Contraceptive Pill on Day Four

Taking emergency contraception on the fourth day?

Hello, can I ask if taking the emergency contraceptive pill on the fourth day will still have a chance of preventing pregnancy? As a student, I cannot afford to be pregnant.
Is it still possible to remedy the situation now?

Niming, 10~19 year old female. Ask Date: 2015/08/01

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello, the effectiveness of emergency contraceptive pills is about 97% when taken within three days.
The effectiveness decreases over time, with studies in Canada showing around 90% effectiveness when taken between three to five days.
There is currently no data on effectiveness beyond that timeframe, and human trials cannot be conducted.
Please remember to check for pregnancy if your period is more than a week late.
Thank you! Wishing you safety and health, Dr.
Zhang.

Reply Date: 2015/08/01

More Info

The effectiveness of emergency contraceptive pills (ECPs), such as EllaOne or Plan B, significantly decreases the longer you wait to take them after unprotected intercourse. Ideally, these pills should be taken as soon as possible after the event, with the highest efficacy observed when taken within 72 hours (3 days). According to various studies, the effectiveness of ECPs can be around 97% if taken within this time frame. However, if taken between 72 to 120 hours (3 to 5 days), the effectiveness drops to approximately 90%, and beyond that, there is limited data available on their efficacy.

In your case, taking an emergency contraceptive pill on the fourth day after unprotected intercourse means you are outside the optimal window for effectiveness. While there is still a chance that the pill may prevent pregnancy, it is significantly lower than if you had taken it earlier. The effectiveness of ECPs diminishes as time passes, and after five days, the data is insufficient to provide a reliable estimate of effectiveness. Therefore, while there may still be a chance of preventing pregnancy, it is not guaranteed.

It is also important to note that if your menstrual period is delayed by more than a week after taking the ECP, it is advisable to take a pregnancy test to confirm whether or not you are pregnant. This is crucial because while ECPs can reduce the risk of pregnancy, they are not 100% effective, especially when taken later than recommended.

In addition to the effectiveness of ECPs, it's worth mentioning that these medications can also affect your menstrual cycle. Some women may experience changes in their cycle, such as an earlier or later onset of their next period, heavier or lighter bleeding, or spotting. These changes are generally temporary and should normalize in subsequent cycles.

If you find yourself in a situation where you are concerned about potential pregnancy, it is essential to consult with a healthcare provider. They can offer guidance on the next steps, including the possibility of a pregnancy test and further contraceptive options to prevent future unintended pregnancies. Additionally, discussing long-term contraceptive methods may be beneficial, especially if you are a student and want to avoid the stress of unintended pregnancy in the future.

In summary, while taking an emergency contraceptive pill on the fourth day after unprotected intercourse may still offer some chance of preventing pregnancy, the likelihood of success is significantly reduced. It is crucial to monitor your menstrual cycle and consult a healthcare professional if you have concerns about pregnancy or your contraceptive options moving forward.

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