I have seen numerous movies with sex scenes:
Friends with Benefits is one, No Strings attached (insertion is not filmed here) and several others where the intercourse is actually on camera (the insertion as well).
This makes me curious as to what sort of conditions and requirements there are for both man and woman as to not cause accidental pregnancy, or transmit any STD, or any internal injuries.
What do film producers do to ensure none of this happens and full safety is applied to the scene itself as well as the actors?