I have 4 rats in a tub without a male. They had had a lot of litters, so I've been letting them have a break. When I took the male out, they already had a litter, and that litter has been euthanized already. Then, without the male, 2 of them got prego and had another litter. Then, after that litter, MORE babies. And now, I just looked and I got ANOTHER one thats prego!

Keep in mind there is not a single male with them. Just the girls.

Did they store sperm inside them and then got prego with that preserved sperm?