He says they have a good doctor. Perhaps the reason he is having his wives tested is so that he can catch them early and....."take care of the situation"

 

I honestly do not know, as that was never really a thing addressed in the comics at all. I actually raised my eyebrows at the pregnancy test thing when it aired.

As far as comic Negan's attitude about kids, the only official thing we have is from the Here's Negan backstory, where it sounds like he doesn't really want them. "Babies are gross" comment, in regards to it being natural for humans to want to screw as much as possible because of the biological instinct to reproduce... "even though babies are gross".

Only other time he directly mentions kids is... hmmm, okay, I should spoiler this one.