My cat's also fixed. I remember my mom explaining to me when I was a little kid that we were "taking Abby and Barbie to make sure they can't have baby kitties, because we don't want to give away baby kitties", and I was bawling because dammit, I wanted baby kitties! I understand now that you should always get your cat fixed and I'm glad we did it before they got pregnant (both are outside cats).
I personally believe that you should get them spayed and neutered, I know that feral cat colonies can be nasty pieces of work and that cats can severely damage the local ecology when their population is left unchecked. Sure, kittens are cute, but when they grow up feral then very bad things happen, very bad things indeed.
