From the Guidelines
The risk of pregnancy in your situation is approximately 1-2% due to the delayed intake of your progesterone-only pill, but this risk is mitigated by the fact that your last sexual encounter was two days ago. Taking a progesterone-only pill (POP) more than 3 hours late (or 12 hours late for desogestrel-containing POPs like Cerazette) reduces its effectiveness 1. Since Amsterdam is one hour ahead of the UK, you took your pill at approximately 4:40 PM UK time yesterday and 8:15 PM UK time today - a gap of about 27.5 hours, which exceeds the recommended 24-hour interval. This delay could temporarily reduce the contraceptive effect, particularly if you had sex during this time. However, since your last sexual encounter was two days ago, before the delayed pill, the risk is lower.
Key Considerations
- Progesterone-only pills work primarily by thickening cervical mucus to prevent sperm entry and sometimes by preventing ovulation 1.
- For maximum protection, take your next pill at your regular UK time and consider using backup contraception (like condoms) for the next 48 hours.
- If you're concerned, emergency contraception is an option, though its necessity depends on which specific progesterone-only pill you're taking and how consistently you've taken it previously 1.
Recommendations
- Take your next pill at your regular UK time to maintain the contraceptive effect.
- Use backup contraception, such as condoms, for the next 48 hours to minimize the risk of pregnancy.
- Consider emergency contraception if you're concerned about the risk of pregnancy, but consult with a healthcare provider to determine the best course of action 1.
From the FDA Drug Label
If levonorgestrel tablet is taken as directed, it can significantly decrease the chance that you will get pregnant About 7 out of every 8 women who would have gotten pregnant will not become pregnant.
The risk of getting pregnant is not explicitly stated as a percentage in the provided text, but it can be inferred that the effectiveness of levonorgestrel tablet is around 87.5% (7 out of 8 women who would have gotten pregnant will not become pregnant) if taken as directed. However, this does not directly answer the question as it does not take into account the timing of the pill intake and the last sexual activity. Given the information provided and the fact that the pill was taken at different times and the last sexual activity was two days ago, no conclusion can be drawn about the exact risk of pregnancy in this specific situation. 2
From the Research
Risk of Pregnancy with Progesterone-Only Contraceptive Pill
- The provided studies do not directly address the specific scenario of taking a progesterone-only contraceptive pill at 5:40 in Amsterdam time yesterday and 20:15 in UK time today, and having sex two days ago.
- However, the studies suggest that the effectiveness of emergency contraception, including progesterone-only pills, decreases with time after unprotected intercourse 3, 4, 5, 6, 7.
- According to the studies, levonorgestrel-only emergency contraception is most effective when taken within 72 hours of unprotected intercourse, with a pregnancy risk reduction of 60 to 94% 5.
- The studies also suggest that ulipristal acetate, a selective progesterone receptor modulator, is more effective than levonorgestrel in preventing pregnancy, especially when taken later than 72 hours postcoitus 4, 6, 7.
- However, without more specific information about the timing and dosage of the progesterone-only contraceptive pill, it is difficult to estimate the exact risk of pregnancy in this scenario.
Factors Affecting Pregnancy Risk
- The studies suggest that factors such as body weight and body mass index (BMI) can affect the efficacy of emergency contraception, with women who weigh more than 75 kg or have a BMI greater than 25 kg/m2 having a higher risk of unintended pregnancy when using oral levonorgestrel EC 6, 7.
- The timing of intercourse and the timing of taking the emergency contraception also play a role in determining the risk of pregnancy, with the risk decreasing as the time between intercourse and taking the emergency contraception increases 3, 4, 5, 6, 7.