Birth control pills are a relatively reliable method of preventing you from becoming pregnant. When they are used properly, that is, they are used consistently and in the exact manner that they are prescribed, birth control pills are 99.9% effective at preventing conception. This means that there is only a 1 in 1000 chance that you could become pregnant while you are on birth control pills. In the real world, where some women will miss a birth control pill, take one late, or not take them exactly as prescribed, the pill becomes less effective, and can make the risk of pregnancy more like 1 in 20, or around 5%. The good news is that, even if you do become pregnant while on birth control pills, there is little risk that they will have harmed your baby.
Once concern that many women have regarding birth control pills is the risk that the pill might present to their baby if they do happen to become pregnant. While this may have been true in the past, it is not necessarily the case today. It used to be that birth control pills had much higher levels of the hormones progesterone and estrogen than are in today’s birth control pills. It was thought that these higher levels of progesterone and estrogen might cause defects or problems in the genitals of the baby, although even research on this point was inconclusive. Even given this fact, it is reassuring to know that modern birth control pills are not though to contribute significantly to birth defects. Still, if you have become pregnant while on birth control pills, you should stop taking them immediately and discuss this with your health care provider.
If you are concerned about any unknown risks that birth control pills might have in harming your baby, you might consider practicing a combination of birth control methods. Because the birth control pill offers no protection whatsoever from STDs, many women choose to use some sort of barrier method, such as the male or female condom, the sponge, or the diaphragm along with their birth control pills. Put together, multiple methods of birth control make pregnancy much less likely.