They have introduced something like this is mainly because just like in the real world teenagers can engage themselves in sex animations and due to that reason teen pregnancy is very much possible. Hence if any Sim wants to check the chance of pregnancy as a percentage, it is also provided in the game and it can be tested by selecting a toilet and choosing 'Fertility Awareness Test.' The default settings that is eventually applied for the Sims who can get pregnant brings on a probability to get pregnant by the animation vaginal sex, but what is more enthusiastic is getting pregnant depends on their menstrual cycle, that is what makes this more realistic.
The settings for this pregnancy can always be changed.
