Is my mouse pregnant?

Question
I have a really chubby female mouse that has been in a cage with my male mouse for 3 weeks now. I hear sqeeking a lot in the cage and I don't know if that means he is still trying to get her pregnant.

What do you think?

Also since she is already fat..

How do I know when to take her out of the cage?

P.s. last time I tried this with a different female mouse and the same male mouse and he didn't get her pregnant and I left her in there for about 3 weeks also.

Answer
Dear Mia,

A female mouse who has never been pregnant will begin to show her nipples more when she becomes pregnant. The fur will push back to reveal skin, so the pups can nurse.

If you see her nipples, separate them now. She might already be quite far along.

I strongly discourage any informal breeding. One major reason is that since male mice usually have to live alone, you will need a separate cage or a separate home for each male. There could easily be 8 or more males in a litter. You need to find homes before you breed, because they grow up fast, and are ready to mate as early as 4-1/2 weeks.

If you do not get it right, you can have hundreds of mice within three months.

Best of luck;

Squeaks n giggles,

Natasha