Question

What happens to the sperm when the women is already pregnent?

Answer 1

sperm will come out side and many of them will dead in side the uterus because its life span is about 2-3 days.
there is no egg(ovum) so no any sperm will fertilize.

Answer 2

 I know of no species (I may stand corrected) where new sperm would disrupt the already happening pregnancy., at least after the first month, it is nearly impossible for any additional sperm to enter the uterus, if that would have any effect on the fetus (which it doesn’t).and sperm can only live 3–5 days, even in the best of conditions. And, chances are, your 8–9 month pregnant wife is not going to really be in the mood anyway.!!!