There are two main forms of birth control offered with the mod. If pregnancy is desired but the Sim to be impregnated is at a 0% chance of pregnancy, the normal 'Try for Baby' interaction can be used. The percent chance of pregnancy can be checked by clicking a toilet and selecting 'Fertility Awareness Test.'
For Sims who can get pregnant, the default settings leave a chance for pregnancy with vaginal sex animations that depend on where that Sim is in their menstrual cycle.
The mod allows changeable settings for pregnancy.