Can You Get Pregnant If You Miss a Pill?

Inconsistent dosing can reduce protection

If you miss taking your birth control pill, or take it at the wrong time, it does increase your chances of becoming pregnant. However, you shouldn't panic or assume that you have no protection at all. The drugs do have some "forgiveness" in that some of the medication will remain in your blood even after a missed dose.

But it's important to remember that the pill is not perfect. While it is 99% effective in women who take their pill on time every day, that percentage drops to 91% in women who do not adhere to a consistent schedule. If you miss more than one dose per cycle or pill pack, the risk of pregnancy can suddenly become very real.

This article discusses how birth control works, why it fails, and what you should do if you miss a dose, so you can lower your odds of becoming pregnant.

Woman holding birth control pills, mid section

PhotoAlto / Ale Ventura / Getty Images

How Birth Control Pills Work

Oral contraceptives work by providing your body with just enough hormones to block ovulation. Ovulation is when an egg is released from the ovaries. Ovulation usually occurs between day 11 and day 21 of the menstrual cycle. Women are most fertile during the two to three days before ovulation.

When you take your pills as prescribed, your body will have a steady supply of medication to keep you from ovulating. We refer to this as maintaining the therapeutic drug level, or how much of the drug needs to be in your system for it to be effective.

To achieve the best results, you will need to take one pill at the same time every day. Missing or delaying doses allows the therapeutic drug level to drop.

  • Over the course of an hour, the drop may not be significant.
  • Over 24 hours, the drop could very well be significant.

Ultimately, there is a point at which drug levels drop low enough that ovulation can occur. This can vary from person to person. The levels drop more quickly in some women than others.

The pill does not terminate a pregnancy; it prevents ovulation. If an egg is released, pregnancy can occur.

Reasons Why Birth Control Pills Fail

In addition to missed or late doses, there are other things that can reduce the effectiveness of birth control pills. Among them:

  • Progestin-only birth control pills, also known as the "mini-pill," have far less forgiveness than "combined" pills that contain both progestin and estrogen.
  • Nausea, vomiting, or diarrhea can lessen the effects of the pill by eliminating too much of the active drug from the body.
  • Antibiotics can also interfere with the pill's effects. Rifadin (rifampin) and, to a lesser extent, penicillin, amoxicillin, ampicillin, Bactrim (sulfamethoxazole/trimethoprim), tetracycline, minocycline, Flagyl (metronidazole), and nitrofurantoin all have known interactions with oral contraceptive medications.

If you missed a dose, especially if it was a progestin-only pill, got sick to your stomach, or were prescribed another medication that may interact with the pill, it's important to consider back-up birth control. This may include using condoms, diaphragms, or sponges.

What to Do If You Miss a Dose

If you are late taking a birth control pill, don't panic. It's only human to forget every now and then. There is no point in beating yourself up about it. Instead, try to identify why you missed the dose.

  • Was it caused by a change in your schedule?
  • Was there an event or incident that distracted you?
  • Did you rush off to work before realizing your mistake?

By pinpointing the cause, you can find a way to avoid missing doses in the future, either by altering your dosing schedule or providing yourself helpful, daily reminders.

If you are late taking a pill, here is what you should do:

  1. Take a dose as soon as you remember. This may mean doubling the dose if you missed an entire day. Read the packet insert for instructions on how and when to double up or call your healthcare provider's office for assistance.
  2. Use a backup method of birth control to help decrease your risk of pregnancy.
  3. Make a note detailing what caused you to miss the dose. Keeping a daily treatment diary is particularly useful if you are just starting out on the pill.

Summary

Taking birth control every day, at the same time each day, is the best way to prevent pregnancy. A steady supply of hormones will keep you from ovulating. However, don't panic if you forget. You may still have some level of protection.

If you miss your pill, take it as soon as you remember and/or use a back-up method of contraception. Keeping a treatment diary may also help you figure out why you missed a dose and how to stay on schedule going forward.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. McCann MF, Potter LS. Progestin-only oral contraception: a comprehensive review. Contraception. 1994;50(6 Suppl 1):S1-195. doi:10.1016/0010-7824(94)90113-9

  4. Dickinson BD, Altman RD, Nielsen NH, Sterling ML. Drug interactions between oral contraceptives and antibiotics. Obstet Gynecol. 2001;98(5 Pt 1):853-60. doi:10.1016/S0029-7844(01)01532-0

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