What is the possibility of getting pregnant while on birth control

  • Effectiveness
    • How likely is it to get pregnant while on the pill?
    • Are birth control pills more effective than condoms?
    • How long does it take for birth control pills to work?
  • Pill Failure
    • What causes the failure of birth control pills?
    • How would you know if you were pregnant while taking the pill?
  • Related Resources
    • Related Resources - How Likely Is It to Get Pregnant While on Birth Control Pills?

How likely is it to get pregnant while on the pill?

What is the possibility of getting pregnant while on birth control

Birth control pills are over 99% effective when taken correctly and regularly as prescribed.

None of the methods used for birth control are 100% effective. There is a possibility, although rare, of getting pregnant while on birth control pills. Birth control pills are over 99% effective when taken correctly and regularly as prescribed.

What causes the failure of birth control pills?

Several factors that may be directly or indirectly related to the failure of birth control pills, causing pregnancy, are:

  • Taking the pills irregularly or at a different time each day
  • Vomiting and diarrhea for more than 48 hours
  • Some antibiotics, antifungals and anti-seizure medicines
  • Some HIV medications
  • The herb St. John’s Wort
  • The pill may not work for people who are overweight

How would you know if you were pregnant while taking the pill?

If a woman on birth control pills gets pregnant, she may notice the following symptoms:

  • Missed periods
  • Nausea and/or vomiting
  • Aversions to certain foods and smells
  • Appetite changes
  • Bloating or water retention
  • Breast pain or tenderness
  • Change in breast size or appearance
  • Fatigue
  • Increased urine frequency
  • Bodyache
  • Mood swings
  • Occasional spotting or bleeding

If you experience any of these symptoms, get a pregnancy test done at home or in a clinic/lab.

Are birth control pills more effective than condoms?

Yes, the typical effectiveness of a pill ranges from 91% to 99%. The failure rate for the pill is 1% to 9%, whereas for male condoms, it is 13% and for female condoms it is 21%.

How long does it take for birth control pills to work?

The time it takes birth control pills to work depends on when you start taking them and what type of pills you use. You may begin taking the birth control pill any day of the month. It is; however, advisable to use a backup birth control method, such as condoms, for about a week once you start taking the pills.

Combination oral contraceptive pills (COCs)

  • When started within five days after the first day of your period, the combined pill will protect you from pregnancy right away.
  • If you get your periods on a Monday morning and you start taking the combined pills any time before Saturday morning, you will be instantly protected from a possible pregnancy.
  • If the pills are started at any other time, it is best to use an additional method of birth control, like a condom, for the first week after you start taking the combined pills.

Progestin-only pills (Mini pills)

  • Progestin-only pills, POPs or mini pills can be started any day of the month. They will protect you from pregnancy after 48 hours (two days) of taking the first pill.
  • In this case, you must use another method of birth control (like a condom) to prevent pregnancy during the first two days.

You must always discuss with your nurse or doctor about which birth control pill option would be best for you.

What is the possibility of getting pregnant while on birth control

QUESTION

Which of the following are methods for contraception? See Answer

References

Medscape Medical Reference

Do birth control pills cause birth defects if taken during early pregnancy?

Answer From Myra Wick, M.D., Ph.D.

Taking birth control pills during early pregnancy doesn't appear to increase the risk of birth defects.

Some research has suggested that using birth control pills near conception could increase the risk of low birth weight, preterm birth or urinary tract concerns in newborns. But in general, health care providers haven't seen those problems occur.

Birth control pills lower the risk of pregnancy. They also reduce the risk of a fertilized egg implanting outside the uterus (ectopic pregnancy). Ectopic pregnancies most often form in one of the tubes that carry eggs from the ovaries to the uterus (fallopian tubes). If you do conceive while taking a progestin-only birth control pill, sometime called the minipill, there is a slightly higher chance that the pregnancy will be ectopic.

As a precaution, if you suspect you're pregnant, take a home pregnancy test. If that test is positive, stop taking the pill. If taking a home pregnancy test isn't possible, stop taking birth control pills until you can see a health care provider to find out if you're pregnant. In the meantime, use another method of birth control, such as condoms.

If you're worried because you took birth control pills before you knew you were pregnant, talk to your health care provider. But know that there is little risk of birth defects.

With

Myra Wick, M.D., Ph.D.

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Aug. 16, 2022

  1. Wick MJ (expert opinion). Mayo Clinic. July 30, 2022.
  2. Kaunitz AM. Ectopic pregnancy: Epidemiology, risk factors, and anatomic sites. https://www.uptodate.com/contents/search. Accessed July 15, 2022.
  3. Charlton BM, et al. Maternal use of oral contraceptives and risk of birth defects in Denmark: Prospective, nationwide cohort study. BMJ. 2016; doi:10.1136/bmj.h6712.
  4. Aronson JK, et al. Hormonal contraceptives — Oral. In: Meyler's Side Effects of Drugs. 16th ed. Saunders Elsevier; 2016. https://www.clinicalkey.com. Accessed July 15, 2022.
  5. Kaunitz AM. Progestin-only pills (POPs) for contraception. https://www.uptodate.com/contents/search. Accessed July 15, 2022.

See more Expert Answers

See also

  1. 1st trimester pregnancy
  2. Ovulation
  3. Fetal development: The 1st trimester
  4. Implantation bleeding
  5. Nausea during pregnancy
  6. Pregnancy due date calculator
  7. Prenatal care: 1st trimester
  8. Pregnancy exercises
  9. Pregnancy stretches

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Is it possible to get pregnant while you are on birth control?

Birth control pills are considered effective, but not foolproof. They're about 99% effective when you take them correctly. But that's if you take them perfectly, meaning at the same time each and every day. If you don't, your odds of becoming pregnant go up to 9%.

How do you tell if you're pregnant while on birth control?

How do you know if you're pregnant on the pill? If you are on the birth control pill, it can take a few days and sometimes even several weeks for pregnancy symptoms to get noticed. Look for early signs of pregnancy, including a missed period, nausea, tenderness in the breasts, and a persisting headache.

What can cause you to get pregnant while on birth control?

The Birth Control Pill Other reasons why your pill might not work include: You're vomiting or have diarrhea for more than 48 hours. You take the antibiotic rifampin, the antifungal griseofulvin, certain anti-seizure meds, or the herbal supplement St. John's wort. You're obese.