Birth Control Pills Failure

Mar 17, 2009
Birth control pill is known to be 92 to 99 % effective in preventing pregnancy. However, you may hear a number of stories, when women got pregnant while on the pill. Many women are concerned about the risk of getting pregnant using birth control pills and what can be done to prevent the failure.

According to the research published in the journal Human Reproduction, around two thirds of unintended pregnancies among women using birth control pills were due to misuse of the pill. What are the possible causes of the birth control pills failure?

Missed pill

It is quite common for women taking birth control pills to miss one or several pills. Many women forget to take the pill or miss it due to different changes in daily routine. Almost half of all the pill users forget to take at least one pill per cycle.

Chances of getting pregnant in case you've missed the pill are quite low as ovulation will not usually occur within 4 days after discontinuing the pill. Only one in ten women will have ovulation 10 days after stopping the pill.

In case, you've forgot to take one birth control pill, you may need to take that missed pill and the next one together and then go on taking the pill according to the schedule. If you missed two or more pills, you will need to continue taking the pill, but use back up contraception (like, condom) until you finish the pack. If your periods has began, you may need to restart taking the pills from a new pack after your periods are off.

Switching the birth control methods

Some women find that their birth control method does not suit them due to unwanted side effects or inconvenience and decide to switch to another birth control option. Changing birth control pills without proper supervision may result in unwanted side effects as well as unintended pregnancy.

It is important to discuss with your gynecologist the appropriate plan for switching to another birth control pills or method of contraception to avoid possible side effects. The risk of pregnancy while changing birth control methods will depend on the type of birth control and the time when you switch to another method.

You should know that if you did not take the pill for seven and more days after your last active birth control pill, you will need to use back up contraception (like condoms) for the first seven days of taking the new birth control pills. If you switch from birth control patch or ring to birth control pills, you may start taking the pills at any point to ensure contraception works continuously. Though the risk of getting pregnant while switching to another pill is quite low, it is recommended to use back up contraception for extra protection.

Illness or other medications

Some medications and health conditions may decrease the effectiveness of birth control pills. This happens due to the fact that medications speed up the metabolism, while birth control pills are metabolized in the liver. The interaction between your medications and birth control pills can sometimes lead to changes in hormone level in the blood and unintended pregnancy.

The most common medications that are known to counteract the effect of birth control pills are various antibiotics and anti-seizure drugs. Also if you have flu, acute gastrointestinal illness or diarrhea, you may need to consult your doctor to find if your condition can decrease the effectiveness of birth control pills.