The male should be neutered and the female spayed, the male can get out and cause other female cats to get pregnant, and the female can get out and get pregnant by other males! cats are happier neutered, male cats get into all sorts of fights looking for females, they also spray around the house, marking their house and it is a nasty smell believe me! females not spayed often get cancer of the womb, besides the terrible noise they make when they are in heat, and they will try everything they can to get out to a male, have them both done.