Q: If my partner is on birth control, is there really a need for a condom as well? Is there much difference in the chance of getting pregnant when the two methods are combined versus only using birth control?
A: Condoms are a great method of preventing birth. If they are used correctly, they can be 98% effective (meaning if 100 couples had sex regularly for a year and they used condoms, only 2 of the 100 would get pregnant by the end of the year. Birth control (oral pills, implants, IUDs, etc.) work even better. If they're used correctly, they are 99.3 - 99.5% effective (only 1 in 200 couples would get pregnant using it in a year).
If your only goal is to prevent pregnancy, there really is no reason you would need more protection than birth control alone. However, condoms are the only form of contraception that can prevent sexually transmitted infections (e.g., herpes, gonorrhea, HIV). If you're absolutely certain that you and your partner do not have STIs, then it's relatively safe to not wear condoms during sex. The other thing to consider, though, is that oral birth control is only effective if a person remembers to take it every single day. Even missing the pill for just two days can greatly reduce its effectiveness in preventing pregnancy. So, in this case, condoms can be a great backup plan.
If your partner is on an oral (pill) form of birth control, she may benefit from getting a more long-lasting form of birth control, such as an implant or IUD. You can find more information on these here. These forms of birth control don't need to be administered every day, so there's no chance of forgetting to take it and becoming unprotected. Studies show these "long acting, reversible contraceptives" (LARCs) tend to be much more effective in reducing pregnancy, even when compared to traditional birth control. In other words, if you're using a LARC and neither of you have an STI, then there really isn't a need to use condoms.
Answers provided by Dr. Ross Avilla
Dr. Ross Avilla has been teaching Human Sexuality since 2013 and has a PhD in psychology from UC Davis. Dr. Avilla is not a clinician and all information and advice offered on this website is for educational purposes only.