More like sex is chosen except if it’s rape. And it’s pretty common sense that it can cause pregnancy unless one or both people are pretty infertile and/or some kind of contraceptive is used.
The biological purpose of sex is for reproduction, and women know that. Therefore, when they choose to have unprotected sex, they are choosing to get pregnant.
Rape is unlikely to result in pregnancy. A woman who has been raped can decrease that small chance by using a “morning after” contraceptive when she seeks medical attention for the rape.