What is an Emergency Contraceptive Pill (ECP)?
An Emergency Contraceptive Pill (ECP) is a dose of medication taken after unprotected sexual intercourse to prevent pregnancy. Often referred to as the "morning-after pill," this term is misleading, as ECPs can be effective for several days after sex, though they are most effective the sooner they are taken. ECPs should be used as a backup, not as a primary, method of contraception, as they are less effective than other forms of birth control.
How Do ECPs Work?
ECPs work primarily by interfering with or delaying ovulation—the release of an egg from the ovary. By delaying this process, ECPs prevent the egg from being released while there is still active sperm in the reproductive tract, preventing fertilization. Different types of ECPs may also have secondary mechanisms of action, such as altering the uterine lining to prevent implantation, though their main function is ovulation suppression. It is crucial to understand that ECPs do not end an already established pregnancy and are not the same as abortion pills.
The Different Types of ECPs
There are two main types of ECPs available in the United States, which contain different active ingredients and have different time windows of effectiveness.
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Levonorgestrel Pills: These pills contain a synthetic progestin hormone called levonorgestrel. Brands include Plan B One-Step, Take Action, My Way, and others.
- Availability: Available over-the-counter at pharmacies for all ages, without a prescription.
- Timeframe: Should be taken as soon as possible, up to 72 hours (3 days) after unprotected sex.
- Effectiveness: Effectiveness decreases over time, making prompt use critical.
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Ulipristal Acetate Pills: This is a more potent ECP that contains a drug called ulipristal acetate. The primary brand name is ella.
- Availability: Requires a prescription from a healthcare provider.
- Timeframe: Effective for up to 120 hours (5 days) after unprotected sex.
- Effectiveness: Remains consistently effective throughout the entire 120-hour window and is considered more effective than levonorgestrel, especially in the later part of the window.
ECP Effectiveness and Factors
Several factors can influence the effectiveness of ECPs:
- Timing is key: The most critical factor is how soon the pill is taken after unprotected sex. Both levonorgestrel and ulipristal acetate are more effective the sooner they are used.
- Weight: Some studies suggest that levonorgestrel-based ECPs may be less effective in individuals with a higher body mass index (BMI), although data is conflicting and women with higher BMI should not be denied access. Ulipristal acetate appears to maintain its effectiveness regardless of weight.
- Other Medications: Certain medications, such as some anti-seizure drugs and the herbal supplement St. John's Wort, can decrease the effectiveness of ECPs.
Potential Side Effects of ECPs
While generally safe, ECPs can cause temporary side effects that typically resolve within a couple of days.
- Nausea and Vomiting: This is a common side effect, though it is more frequent with older, combined hormone ECPs. Taking the pill with food can help. If vomiting occurs within 2-3 hours of taking the pill, a healthcare provider should be consulted as another dose may be needed.
- Changes to Menstrual Cycle: Your next period may be earlier or later than usual, or the flow may be lighter or heavier. Spotting or bleeding between periods is also possible.
- Other Side Effects: Other common, mild side effects include headaches, dizziness, fatigue, breast tenderness, and abdominal pain.
Comparison of ECPs and Regular Birth Control
| Feature | ECPs (Emergency Contraceptive Pills) | Regular Birth Control Pills | |
|---|---|---|---|
| Usage | One-time, backup contraception after unprotected sex or contraceptive failure. | Taken daily for ongoing, continuous contraception. | |
| Effectiveness | Lower effectiveness than regular birth control. Plan B is around 75-89% effective within 72 hours; ella is more effective, especially up to 5 days. | Higher effectiveness. Combination pills are >99% effective with perfect use. | |
| Hormone Dose | A single, high dose of hormones. | Low, consistent daily dose of hormones. | |
| Protection against STIs | No protection against Sexually Transmitted Infections (STIs). | No protection against STIs. | |
| Cost | Can be more expensive per use than regular birth control, especially for frequent use. | Cost-effective over time for regular, ongoing use. |
The Next Steps if an ECP Fails
ECPs are not 100% effective, and there is a small chance of pregnancy even with perfect use. If your period is more than a week late after taking an ECP, you should take a pregnancy test. If the test is positive, it means the ECP was unsuccessful, and you should consult a healthcare provider to discuss your options. ECPs do not pose a risk to the developing embryo if a pregnancy continues. It is also important to remember that ECPs do not protect against STIs, so if there is a risk of exposure, testing may be necessary.
Conclusion
An ECP pill is a vital backup option for preventing pregnancy in emergency situations, such as contraceptive failure or unprotected sex. Understanding the difference between levonorgestrel (Plan B) and ulipristal acetate (ella) is important, particularly regarding their timeframes of effectiveness and accessibility. While effective when used correctly, ECPs are not a substitute for regular, ongoing birth control and do not protect against sexually transmitted infections. Anyone who has questions about ECPs, or experiences a failure, should consult a healthcare provider to explore further options and long-term contraception methods.
For more information on emergency contraception, you can visit the Planned Parenthood website: https://www.plannedparenthood.org/learn/morning-after-pill-emergency-contraception.
