Can You Get Pregnant On The Pill?

Even if you take the pill correctly, there’s still a very small chance of failure because it is not 100% effective. The chances of getting pregnant while on the pill depend on whether you are taking it ‘perfectly’ or ‘typically’.

• Perfectly: when taken perfectly, both the combined pill and the mini pill are over 99% effective. That means that for every 100 people taking the pill exactly as prescribed, fewer than 1 will get pregnant in a year.
• Typically: when taken typically, the effectiveness of either pill falls to about 91%. Typical use includes things like missing 1 or more pills, taking them late, or being sick (vomiting).

Am I protected during the break week?

Yes, you are protected against pregnancy during your pill-free break as long as you took your pills correctly for 21 days and start your new strip on time, usually on day 8.

Pregnancy on the mini pill vs combined pill

Pregnancy is equally possible on the mini pill or the combined pill.

Their effectiveness is exactly the same for perfect use (more than 99% effective) and typical use (91%). This means 9 in 100 women who take either pill will get pregnant in a year, unless the pill is taken perfectly the whole time, in which case, this is reduced to less than 1 in 100 women.

Several factors can cause the contraceptive pill to fail or make it less effective, including:

Missed or late pills

The most common reason for the pill to fail is not using it consistently or correctly, such as forgetting to take it, taking it at different times each day, or making other user errors. All of these factors can reduce the effectiveness of the pill, increasing the chances of pregnancy.

Most mini pills come with a ‘window period’ in which you must take them, which is how late you can be at taking the pill compared to what time you took it the day before. For instance, 3-hour mini pills must be taken within 3 hours of the time you took them the day before, and 12-hour mini pills need to be taken within 12 hours of the day before.

For the combined pill, a pill is considered late if taken more than 24 hours after the usual time.

If you miss the window period, this counts as a missed pill, and you should follow the instructions in your patient information leaflet on what to do next.

Being sick or having diarrhoea

Sickness (vomiting) or diarrhoea can make the pill less effective because it can mean that the active ingredients have not yet been absorbed.

• If you are sick within a few hours of taking the pill, you should take another straight away.
• If you continue to be sick or have prolonged diarrhoea, you’ll need to use another method of contraception, like condoms, for as long as your contraceptive pill information tells you to.

Commonly, for combined pills, it’s advised to use condoms for 7 days after you feel better, and for mini pills, this is 2 days. However, some pills are different, so you should always check the patient information leaflet or speak to a pharmacist.

Drug interactions

Some medications can interfere with the effectiveness of the pill, including:

• some antibiotics
• anti-epileptic medications
• herbal remedies, such as St John’s wort

It’s important you let your doctor know about any other medications you are taking, including prescription, over-the-counter, and herbal types, before starting the pill or if you’re starting on a new medication while taking it.

Incorrect storage

Not storing your pills correctly can make them less effective. They can start to break down and become less potent if they are exposed to:

• heat
• air
• light
• moisture

The contraceptive pill is best stored in a cool, dry place, such as your bedroom drawer. The packet should be kept away from direct sunlight, extreme temperatures, and humidity (making bathrooms unsuitable). You should also make sure the foil of each blister is properly sealed.

Starting or stopping pills incorrectly

When you start your pill for the first time matters, as it may take time to be effective or it may work straight away.

For instance, if you start taking most types of combined pill (with some exceptions, such as Qlaira) for the first time later than day 5 of your menstrual cycle, you will not be protected against pregnancy straight away, so you should use condoms for at least 7 days. However, if you do not and you have unprotected sex, there is a chance you can get pregnant.

When you should start your particular contraceptive pill for it to be effective will be listed in the patient information leaflet, or your doctor may tell you the best time to start it. Some pill brands are different from the norm, so always check to make sure. For instance, Qlaira can only be started on day 1 of your menstrual cycle to be effective straight away, or you must use condoms for 9 days.

Equally, if you stop taking your pill, you can get pregnant as soon as you stop. So, if you do not want to get pregnant, you will need to consider another type of contraception.

The signs of pregnancy are the same as those that occur if you are not using any contraception. However, many pregnancy symptoms can also be side effects of the pill, so the only way to be sure is to take a pregnancy test. Some of the common signs of pregnancy are:

• feeling or being sick (nausea or vomiting)
• changes to menstrual bleeding, including no bleeding, spotting, or lighter than usual
• feeling exhausted, tired, or fatigued
• needing to pee more often than usual
• tender or swollen breasts
• losing interest in certain foods or smells, or having cravings

Does the pill affect pregnancy test results?

No, the contraceptive pill does not affect pregnancy test results because it does not contain the hormone human chorionic gonadotropin (hCG) that pregnancy tests measure.

Home pregnancy tests work by detecting hCG in urine, a hormone that the body only produces during pregnancy. The combined pill contains synthetic versions of oestrogen and progesterone, whereas the mini pill only contains artificial progesterone.

Some of the things you can do to limit the chances of getting pregnant while taking the pill include:

• take your pill at the same time every day to avoid a missed pill
• use an app or set a reminder on your phone to track your pill – it can also help to start on the correct day and follow the pill packet, which is marked with the days of the week
• use condoms if you forget your pill, are late taking it, or are taking any medications that interact with it
• store your pill away from heat, light, and moisture, and not in the bathroom
• follow the instructions in the patient information leaflet if you are sick or have diarrhoea
• speak to your doctor, nurse, or pharmacist if you have any concerns about taking the pill