Medically the evaluation by Deborah Weatherspoon, Ph.D., R.N., CRNA — composed by Rachel Nall, MSN, CRNA ~ above January 28, 2020

Birth manage pills space a popular and effective technique of contraception. However, part factors, together as missing pill days, vomiting, and also taking particular medications, can reduce the effectiveness of the pill and may an outcome in unintentional pregnancies.

You are watching: How likely is it to get pregnant on the pill

In this article, we look at how reliable the birth control pill is, and five reasons why the pill can fail. We additionally give tips on how to protect against pill failure and also describe some early on signs that pregnancy.

Share on PinterestPeter Dazeley/Getty Images
The combined pill has hormones that avoid ovulation, i m sorry is when the ovaries relax an egg because that fertilization. Another kind of pill, recognized as the minipill, reasons a who cervical rubber to thicken and the uterine lining to thin, which reduces the likelihood of sperm reaching an egg.

The birth manage pill is very effective if a person takes it correctly and also does no miss any type of pill days. Follow to the Centers for disease Control and also Prevention (CDC), the pill is 99.7 percent reliable with perfect use. This means that less than 1 out of 100 women that take the pill would end up being pregnant in 1 year.

However, with common use, the performance of the pill is 91 percent. This means that about 9 the end of 100 ladies would come to be pregnant in a year of acquisition the pill.

Five reasons for pill failure

Although the birth control pill is generally very effective, some situations can reduce its effectiveness and also may sometimes an outcome in unintentional pregnancies. These include:

Missing a day

Manufacturers intended for people to take the pill day-to-day for it come be most effective. If a human misses a day, your hormone levels might not stay at consistent enough level to protect against pregnancy.

If a human finds it challenging to take it the pill top top a everyday basis, various other birth manage methods may better suit their needs. A physician or gynecologist deserve to advise top top the variety of alternate contraceptives.


Sometimes a human may it is in ill when they take it the pill. Once a human vomits, the pill deserve to come ago up, or they might not fully absorb it right into their body.

Anyone who experiences vomiting soon after taking the pill need to take an additional pill as quickly as possible and climate take their following pill as usual.

Not acquisition the pills in ~ the very same time each day.

In addition to taking birth manage pills daily, a human being should also take the pills at approximately the same time every day. This deserve to maintain their hormone levels an ext consistently.

A human should constantly take the minipill in ~ the very same 3-hour time window every day. Someone who misses their window should use a backup birth control an approach for the next 2 days or avoid having sex.

Many people collection a daily alarm reminding them come take their pill at the correct time each day.

Not starting a brand-new pack ideal away

It is crucial to begin a new pack that pills the work after finishing the previous one. However, occasionally a human being may not have their new package yet. Absent a couple of days between packs have the right to make the pill less effective at avoiding pregnancy.

According come the CDC, anyone who misses 2 or more pills in a row should use a back-up contraceptive an approach or stop sexual intercourse until they have taken the birth control pill for 7 consecutive days.

Medications that interfere v the pill

Some medications have the right to make the pill much less effective. Drugs include specific antibiotics, such as rifampicin, and anti-fungal drugs, such together griseofulvin.

A human being should use back-up contraception while taking these medications and also for 48 hours after finishing the course.

Other more long-term medications and supplements might also influence how fine birth regulate pills work. These have the right to include:

St. John’s Wort, i beg your pardon is a herbal remedy

Birth control pills are an extremely effective if a human being takes castle correctly and also does no miss any type of pill days. The following tips can help prevent unintended pregnancies while acquisition the pill:

reading the packaging and also following the indict carefullytaking the pill in ~ the very same time every dayalways gaining a new pill load at the very least 1 week before the last pill fill is as result of run outalways acquisition missed pills as shortly as possibleusing a backup an approach of contraception, such as a condom, if a person misses taking 2 or much more pills in a row

If a human being is concerned around not gift able come take their pills consistently, they should speak to their physician or gynecologist around other birth regulate methods. Over there are number of options easily accessible that perform not require taking a pill daily, such together an intrauterine device, or IUD.

If a person is concerned about contraceptive failure and the opportunity of being pregnant, they must speak to their doctor. However, there are also some early on signs that have the right to indicate pregnancy:

Bloating. When bloating is frequently a symptom the premenstrual syndrome, it have the right to sometimes likewise be a authorize of beforehand pregnancy.Light spotting. A little amount of bleeding or spotting can happen when one egg attaches to the uterine lining. If spotting occurs outside of an expected menstrual cycle, it might be an early symptom of pregnancy.Unexplained fatigue. Hormonal changes that occur in the body during pregnancy have the right to make a person feel tired, even throughout the beforehand stages.Urinating much more often. Hormonal changes can rise a woman’s need to urinate throughout early pregnancy.

Anyone who thinks they could be pregnant may wish to take an at-home pregnancy test. These tests have become much more sensitive to a person’s hormone level and much better at detecting pregnancy in its faster stages.

See more: How Long Was The Oj Trials, How Long Did The Oj Simpson Trial Last

However, at-home pregnant tests still may not trustworthy if an individual takes it too early on or does not follow the accuse correctly. Follow to the United claims Food and also Drugs management (FDA), for most reliable results, a human being should take the check 1–2 weeks after ~ their very first missed period.