Emergency Contraception: Its Effectiveness and Risks - Obstetrics and Gynecology

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Emergency contraception (EC) is a method used to prevent pregnancy after unprotected sexual intercourse or contraceptive failure. The most common forms of emergency contraception include hormonal pills, such as levonorgestrel (Plan B) and ulipristal acetate (Ella), and the copper intrauterine device (IUD). Understanding the effectiveness and potential risks associated with these methods is crucial for anyone considering their use.


Effectiveness of Emergency Contraception
The effectiveness of emergency contraception largely depends on how soon it is taken after unprotected intercourse. For hormonal pills like levonorgestrel, they are most effective when taken within 72 hours (3 days) after the event, with a decreasing efficacy up to 120 hours (5 days). Ulipristal acetate can be taken up to 120 hours after intercourse and maintains its effectiveness better than levonorgestrel as time passes.

When taken as directed, hormonal emergency contraceptive pills can reduce the risk of pregnancy by up to 89%. However, it is important to note that they are not 100% effective. Factors such as the timing of ovulation in the menstrual cycle and the individual's body weight can influence their effectiveness.

Risks and Side Effects
While emergency contraception is generally safe, it can cause side effects. Common side effects include nausea, vomiting, fatigue, headache, dizziness, breast tenderness, and changes in the menstrual cycle. The nausea and vomiting you mentioned in your question could be a side effect of the emergency contraceptive pill. If vomiting occurs within two hours of taking the pill, it is advisable to consult a healthcare provider, as another dose may be necessary.


Pregnancy Concerns
Regarding your concern about whether your girlfriend might be pregnant despite taking the emergency contraception correctly, it is important to understand that while the pills significantly reduce the chance of pregnancy, they do not eliminate it entirely. If she experiences symptoms such as nausea or vomiting six days after taking the emergency contraceptive, it could be due to the side effects of the medication rather than pregnancy. However, if her menstrual period is delayed or she experiences other signs of pregnancy, it would be prudent to take a pregnancy test or consult a healthcare professional for further evaluation.


Cases of Pregnancy Despite Taking Emergency Contraception
There are documented cases where individuals have become pregnant even after taking emergency contraception as directed. This can occur due to several reasons, including:
1. Timing of Ovulation: If ovulation has already occurred before taking the emergency contraceptive, the pill may not be effective.

2. Weight: Some studies suggest that emergency contraceptive pills may be less effective in individuals with a higher body mass index (BMI).

3. Drug Interactions: Certain medications can reduce the effectiveness of emergency contraceptive pills, such as some anti-seizure medications and herbal supplements like St. John's Wort.


Conclusion
In summary, while emergency contraception is a reliable method to prevent pregnancy after unprotected intercourse, it is not foolproof. Side effects such as nausea can occur and may not necessarily indicate pregnancy. If there are concerns about pregnancy, especially if her menstrual cycle is late, a pregnancy test is recommended. It is always best to consult with a healthcare provider for personalized advice and to discuss any ongoing concerns regarding contraception and reproductive health.