This question comes from a Catching Health follower:
Can you get pregnant on birth control?
The answer from Carrie Levine, a certified nurse midwife at Whole Woman Healthcare.
The short answer is yes. You can get pregnant on oral contraceptive pills. You can get pregnant with any contraceptive method. The only contraceptive method that works 100% of the time is abstinence. The best way to reduce the risk of unintended pregnancy when you’re using any kind of birth control is to use it correctly. For instance, you can greatly decrease the risk of getting pregnant using oral contraceptive pills by:
1) Taking them exactly as prescribed, which is typically every day.
2) Following protocol if you miss a pill or two.
3) Using a backup method of contraception if you are taking birth control pills and antibiotics at the same time. [Research has shown that the drug rifampin, which is used to treat tuberculosis, can interfere with birth control pills. However, there appears to be little evidence for other antibiotics. Some health care professionals believe more research is needed and recommend back up birth control methods, such as a diaphragm or condom, to be on the safe side.]
Comparing effectiveness of birth control methods
How effective are the various forms of birth control when used correctly? This chart from the Centers for Disease Control and Prevention gives an overview.