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Chance of Pregnancy on the Pill

Are you wondering about your chances of pregnancy on the Pill? You may be asking this question because you’ve been using the Pill for birth control but you’re experiencing pregnancy symptoms; you’re afraid it may have failed you. Or maybe you just want to know how secure you should feel in relying on the Pill to avoid unplanned pregnancy. For whatever reason you are asking, you may have concerns about the effectiveness of this birth control method.

We’ve researched some information and shared it in this article on chances of pregnancy on the Pill. We hope this will be helpful for you. We also hope if you’re facing the possibility, or reality, of an unplanned pregnancy, you will choose to follow up with us at Avenue Women’s Center for further assistance. We are the first step for women in Chicagoland who are experiencing an unplanned pregnancy. Beginning with a medical-grade pregnancy test and a pregnancy consultation with an experienced client advocate, we are here to aid you. Both of these, and many of our other services, are free of cost to you. Please contact us today and allow us to come beside you through this challenging time.

How effective is the Pill in preventing pregnancy?

Ideally, when taken exactly as it should, at the right times, and without any misses, the Pill is generally considered very effective. Multiple sources indicate 97-99% effectiveness when used correctly and consistently. Unfortunately, 100% perfect use of the Pill is rare. Mistakes or missteps while using the Pill can increase the chances of pregnancy on the Pill.

What factors impact the chances of pregnancy on the Pill?

  • Not taking the pill at the same time each day
  • Taking the pills out of order
  • Skipping a pill or missing a dose – If you miss two or more, you’d be wise to use a back-up contraceptive method for a time until you get back on your correct cycle. Check with your doctor or provider to know what to do based on the specific pill you are using.
  • Starting a new pack late
  • Starting the Pill at the wrong time in your menstrual cycle
  • Vomiting within 2 hours of taking a pill, or diarrhea after taking the pill – If it’s possible your body did not have enough time to absorb the hormones, pregnancy prevention may be compromised. Again, check with your doctor.
  • Using other medications or herbal supplements with the pill –Be sure your doctor knows about any supplements or medications, prescription or over-the-counter, you use in order to avoid possible troublesome combinations.
  • Storing your pills in adverse conditions; too much cold, heat, or humidity can have a negative effect on the absorption of the hormones

What should I do now?

If you are just beginning to use birth control pills for contraception, it’s good for you to be aware of these potential pitfalls so you can avoid them. Ask your doctor about any areas in which you have questions.

If you have been using an oral contraceptive and think you may be pregnant, is it possible one or more of the above circumstances may have impacted the effectiveness of the Pill? If yes, or if your pregnancy is confirmed in spite of using the Pill, here are some steps for you:

  • If you haven’t already, find out for certain whether or not you are pregnant. CareNet’s free pregnancy test is 99.5% accurate when taken ten days after the possible time of conception.
  • Identify someone knowledgeable and trustworthy in whom you can confide to explore your options and to walk with you as you determine the course of action that’s best for you. We can provide a caring, listening ear, a comfortable, safe place to work through your decision-making process, and non-judgmental follow through, whatever course you choose. All services at CareNet are strictly confidential.
  • Know that you don’t need to go through this challenging situation alone.

Chances of pregnancy on the Pill? It happens. If it’s happened to you, contact Avenue Women’s Center for an appointment at one of our five DuPage County locations – Elmhurst, Glen Ellyn / Lombard, Naperville, West Chicago, or Wood Dale, Illinois. Call, text, email or chat with us today. That’s what we’re here for. It will be our honor to take this journey with you.


  • American College of Obstetricians and Gynecologists (ACOG). FAQ 129, Seizure Disorders and Pregnancy. Retrieved from:
  • Association of Reproductive Health Professionals (ARHP). (2007, January). Health Matters Fact Sheet, Using Birth Control Pills Regularly for Successful Contraception. Retrieved from:
  • University of Pittsburgh Medical Center (UPMC). Birth Control Pills — Combined Oral Contraceptives. Retrieved from:
  • Infectious Disease Society of America (IDSA). What is an Infectious Disease Specialist? Retrieved from
  • Mayo Clinic. (2016, May). Birth Control. Retrieved from:
  • MedlinePlus, US National Library of Medicine. Search Results for: effectiveness of birth control pills. Retrieved from:
  • UpToDate. (2017, June). Patient education: Hormonal Methods of Birth Control (Beyond the Basics). Retrieved from:
  • Healthliine. (2016, February). Is There a Chance of Getting Pregnant While Taking Birth Control? Retrieved from:
  • Healthline. (2016, October). Can You Get Pregnant on the Pill? Retrieved from:
  • BabyMed. Tips for Safely Storing the Pill. Tips for Safely Storing the Pill. Retrieved from:

Reviewed by Patricia Kuenzi, APN-CNP, MSN, ANP, PNP.

The information provided here is general in nature.  It is not a substitute for a consultation with a medical professional. Before any medical procedure, it is imperative that you discuss your personal medical history, risks, and concerns with your doctor. If you have questions during or after a procedure, your doctor should be immediately contacted. Avenue Women’s Center is not an emergency center.  If you are experiencing severe symptoms, such as bleeding and/or pain, seek immediate medical attention.  Contact your physician, go to an emergency room, or call 911.