If she is pregnant she is not very far along yet. When you see her close to term you'll see what I mean. When she looks like she swollowed a couple golf balls and can't possibly get any larger~ she'll get a little larger yet and then drop the pups. (First litter she may not get quite as fat as I described)
It's probably best that she is not too close anyway. The male is less likely to kill the pups if he has been with the female for a while~ and she is more likely to allow him to breed imediately if they have been together for a while. If she does let him breed right away you can expect another litter in 3 weeks.
Not to argue with the other poster~ to each his/her own~ but I would not suggest moving the female. In fact I would suggest you put together your colony (one male and however many females~ 3 to 5) and leave it that way. Mice are hatefull~ you move that female out your not building trust~ your breaking the colony and may get the female killed when you try to re-introduce her.
Also~ Nothing wrong with picking a mouse up by the tail. Never seen it to seem to stress the mouse any more than just picking it up. Rats sometimes are too heavy and you can tell lifting by the tail is painfull~ mice don't seem to have that problem.
Good luck.
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Cheryl Marchek
AKA JM
Check out my website at:
The Red Dragons Den