Yes, you can get pregnant while taking period delay tablets, because these tablets do not prevent pregnancy
Period delay tablets (also called norethisterone) postpone your period by a few days or weeks. They work by changing hormone levels to prevent the uterine lining from shedding. They do nothing to stop sperm from reaching an egg or to prevent fertilisation. If you have unprotected sex while taking them, pregnancy can happen.
The confusion often comes from the fact that period delay tablets are hormonal. Birth control pills are also hormonal, but they work differently — they prevent ovulation (the release of an egg) or thicken cervical mucus to block sperm. Period delay tablets do neither. They only delay bleeding.
If you need both pregnancy prevention and period control, you need a separate contraceptive method. Period delay tablets are not a substitute for condoms, hormonal contraception, or other birth control.
Key Takeaways
- Period delay tablets contain norethisterone and postpone menstruation but do not prevent ovulation or fertilisation.
- Using period delay tablets without a separate contraceptive method leaves you at full risk of pregnancy.
- If you are taking period delay tablets and want contraception, you must use condoms, birth control pills, an IUD, or another method at the same time.
- Pregnancy can occur at any point during the cycle when you are taking period delay tablets, including while bleeding is delayed.
- If you think you might be pregnant while taking these tablets, a pregnancy test will show a result regardless of whether you are taking them.
How period delay tablets work versus how contraception works
Period delay tablets contain norethisterone, a synthetic progestin. When you take them, usually starting three days before your period is due, they maintain the uterine lining and prevent it from breaking down. Your period does not come because the biological signal to shed the lining is blocked. Once you stop taking the tablets, your period usually arrives within two to three days.
Contraceptive pills work on a different system. They prevent ovulation — the release of an egg from the ovary. Without an egg, there is nothing for sperm to fertilise. Some contraceptive pills also thicken cervical mucus to make it harder for sperm to travel. Period delay tablets do neither of these things. Your ovaries still release an egg on schedule.
This is why the two are not interchangeable. A period delay tablet will not prevent pregnancy. A contraceptive pill will not reliably delay your period (though some people use certain birth control pills continuously to skip periods, which is a different approach).
What happens to fertility while taking period delay tablets
Your fertility window — the days when you can become pregnant — does not change when you take period delay tablets. If you normally ovulate around day 14 of your cycle, you will still ovulate around day 14, even if your period is delayed by a week. The tablets only hide the bleeding; they do not stop the egg from being released.
This means unprotected sex at any point in your cycle carries the same pregnancy risk it always does. If you have sex during your fertile window (usually the five days before ovulation and the day of ovulation itself), pregnancy can occur whether or not you are taking period delay tablets.
Some people mistakenly believe that delaying a period also delays ovulation. It does not. The egg is still released on the normal schedule. The only thing delayed is the bleeding.
Pregnancy risk during different parts of your cycle on these tablets
The pregnancy risk is highest during your fertile window, which typically falls in the middle of your cycle. If you are taking period delay tablets, this window is still there — it is just hidden because you are not bleeding.
Early in your cycle, before ovulation, pregnancy risk is lower but not zero. After ovulation, if fertilisation has not occurred, pregnancy risk drops sharply. But until your period actually arrives, you cannot be certain ovulation has passed.
The safest approach is to assume you can become pregnant at any time unless you are using a contraceptive method that actually prevents ovulation or fertilisation — such as condoms, birth control pills, an IUD, an implant, or a shot.
What to do if you need both period delay and pregnancy prevention
If you want to delay your period and also prevent pregnancy, use a contraceptive method alongside the period delay tablets. Condoms are the most straightforward option because they work when ready and do not interact with the tablets. They also protect against sexually transmitted infections.
If you are already using hormonal contraception (birth control pills, a patch, a ring, or a shot), you can take period delay tablets at the same time. The contraceptive is still working to prevent ovulation. The period delay tablets straightforward postpone the bleeding that would normally occur during your pill-free week.
If you use an IUD or implant, those methods are always working and will continue to work while you take period delay tablets. Again, the tablets only delay bleeding — they do not interfere with the contraceptive.
Talk to a pharmacist or doctor before combining any medications. In most cases, period delay tablets are safe to use with other contraceptives, but it is worth confirming for your specific situation.
Signs of pregnancy while taking period delay tablets
Pregnancy symptoms can appear even while you are taking period delay tablets and your period is delayed. Early signs include breast tenderness, nausea, fatigue, and frequent urination. These symptoms can overlap with side effects of the tablets themselves (which may include nausea, headache, or breast tenderness), so they are not always a clear signal.
The only reliable way to know if you are pregnant is to take a pregnancy test. A test will show a positive result regardless of whether you are taking period delay tablets, because the test detects the hormone human chorionic gonadotropin (hCG), which is produced during pregnancy. The tablets do not interfere with this hormone or with the test.
If you think you might be pregnant, take a test at least 12 to 14 days after unprotected sex for the most reliable result. If the test is negative but you still have symptoms or missed bleeding, repeat the test a few days later or contact a doctor.
When to contact a doctor about period delay tablets and pregnancy concerns
Contact a doctor or pharmacist if you have had unprotected sex while taking period delay tablets and are concerned about pregnancy. They can discuss your options, which may include a pregnancy test, emergency contraception (if you are within the window for it), or other support.
Also speak to a doctor if you are taking period delay tablets and want to start using contraception, or if you are already using contraception and want to know whether it is safe to add period delay tablets. Different contraceptive methods have different interactions and timing rules.
If you become pregnant while taking period delay tablets, the tablets will not harm the pregnancy, but you should stop taking them and contact your doctor for guidance on next steps.
Frequently Asked Questions
Do period delay tablets prevent pregnancy?
No. Period delay tablets only postpone bleeding. They do not prevent ovulation or stop sperm from reaching an egg. You need a separate contraceptive method — such as condoms, birth control pills, or an IUD — to prevent pregnancy.
Can I use period delay tablets instead of birth control?
No. Period delay tablets are not contraception. They are designed only to postpone menstruation for a few days or weeks. If you need pregnancy prevention, you must use a method that actually prevents ovulation or fertilisation.
Will a pregnancy test work if I am taking period delay tablets?
Yes. A pregnancy test detects a hormone produced during pregnancy and will show an accurate result whether or not you are taking period delay tablets. The tablets do not interfere with the test or with pregnancy itself.
Can I take period delay tablets and birth control pills at the same time?
Yes, in most cases. If you are already using hormonal contraception, you can take period delay tablets during your usual pill-free week to postpone bleeding. The contraceptive continues to work. Always check with a pharmacist or doctor first for your specific situation.
What should I do if I had unprotected sex while taking period delay tablets?
Contact a doctor or pharmacist as soon as possible. Depending on how long ago the sex occurred, emergency contraception may be an option. You can also take a pregnancy test 12 to 14 days after the sex for a reliable result.