ooooooooo mice not rats... I was about to say, rats can't get pregnant until 6 weeks.. mice I'm clueless about
also, why not spay mice? I have two spayed female rats because they were possibly pregnant... it turned out they weren't, but their mother was (she was spayed as well). I don't know if mice can be spayed or not.... I know boy mice can be neutered fairly easily
2 rats, 2 mini rex bunnies, 2 cats, 1 prairie dog, 4 species breeding millipedes, 23 various different species tarantulas, 2 Heteropoda davidbowie huntsman spiders, 3 Liocheles australasiae scorps, 20+ Hogna helluo wolf spiderlings, etc.
spiders are addictive... and super easy to care for!