On Wikipedia there's a list of youngest birth mothers, so maybe for some rapists it can be thought of as a competition to get their victim on that list or to even beat the top score - 5 years and 7 months.
I dont think trying to beat that record is worth the legal risk.
You can get away with making a female pregnant when she is 13+ since the judicial system may ignore it as a victimless crime assuming you are not old or unsesirable in other ways.
I can see if i can find the instagram if the girl that got pregnant at 13, nothing happened to her chad boyfriend and i believe they are still together.