There’s an old joke: “Do it the Catholic way!”
Girl asks, “What’s the Catholic way?”
Catholic replies, “Well instead of using contraceptives, you time when you have sex to align with the times you are not ovulating. It’s sometimes called The Rhythm Method. It takes effort and tracking to understand your body, but women have been using this method for centuries.”
Girl replies, “Ok, great!”
[a few months elapse]
Girl says, “Hey, I’m pregnant!”
Catholic replies, “Oh, how blessed!”
Girl says, “But I was doing birth control the Catholic way and it didn’t work!”
Catholic replies, “Oh no, dear. This *is* how it works!”
Seriously, though. Contraceptives fail at low rates. Other methods fail at high rates. If you both want to have sex *and* don’t want to become pregnant, you should use contraceptives.
Other methods, like the rhythm method or having the man pull out before ejaculating work some of the time. If you want to be not-pregnant all of the time your choices are either: 1. Don’t have sex (abstinence), or 2. Use some form of contraceptive (condoms, birth control pills, an IUD, etc.).
I’m sorry that life is unfair this way.
On the bright side, humans before you invented contraceptives so that women have at least *some* choice in the matter. 100 years ago your only option would have been abstinence.