From the Guidelines
You are not fully protected against pregnancy due to the timing of your progesterone-only pill (POP) doses. The time difference between your doses (approximately 38.5 hours, considering the 1-hour time zone difference between Amsterdam and the UK) exceeds the recommended interval for POPs, as a dose is considered missed if it has been >3 hours since it should have been taken 1. Progesterone-only pills need to be taken within a strict time frame each day, and the protection begins to decrease after this window.
To understand the implications, consider the following key points:
- A missed dose is defined as one that is taken more than 3 hours late 1.
- Peak serum steroid levels are reached about 2 hours after administration, followed by rapid distribution and elimination, such that by 24 hours after administration, serum steroid levels are near baseline 1.
- An estimated 48 hours of POP use was deemed necessary to achieve the contraceptive effects on cervical mucus 1.
Given this information, to restore full contraceptive protection, continue taking your pills at the same time each day going forward, and use a backup contraception method like condoms for the next 48 hours, as recommended for missed POPs 1. If you had unprotected sex during this period of reduced protection, you might want to consider emergency contraception and consult with a healthcare provider about your specific situation and pill formulation.
From the Research
Understanding Progesterone-Only Contraceptive Pills
- Progesterone-only contraceptive pills are a type of birth control that contains only progestin, which is a synthetic form of the hormone progesterone 2, 3.
- These pills work by thickening the mucus in the cervix, making it harder for sperm to reach the egg, and also by preventing ovulation in some cases.
Time Zone and Contraceptive Pill Timing
- Amsterdam is in the Central European Time (CET) zone, which is 1 hour ahead of the UK time zone (Greenwich Mean Time, GMT) during standard time and 2 hours ahead during daylight saving time.
- Assuming the times given are in standard time, 5:40 AM in Amsterdam would be 4:40 AM in the UK.
- Taking the pill at 5:40 AM in Amsterdam and then at 20:15 (8:15 PM) in the UK time the next day means there is approximately a 27-hour gap between the two doses, considering the time difference.
Contraceptive Coverage
- The general guideline for taking progesterone-only pills is to take them at the same time every day to maintain contraceptive coverage 4, 5.
- Missing a pill or taking it more than 3 hours late can reduce the effectiveness of the contraceptive and may require additional contraceptive measures, such as emergency contraception, if unprotected sex occurs 6.
- Given the 27-hour gap between doses in this scenario, it's possible that contraceptive coverage may be compromised, especially if the gap exceeds the recommended 3-hour window for progesterone-only pills.
Emergency Contraception
- If there's concern about contraceptive coverage due to missed or delayed pills, emergency contraception can be considered to prevent pregnancy after unprotected sex 2, 3, 4, 5, 6.
- Emergency contraception methods include oral medications like levonorgestrel and ulipristal, and the insertion of a copper intrauterine device (IUD), which can be effective when used within a certain timeframe after unprotected sex.