Mouse meets male

Question
I bought two female mice a week ago. Just the other day I bought a male. I put my frendlyer female in with him. I don't know if she is pregnant or not but she refused when he tried to hump her. Could she be pregnant? And when she gives birth do i need to assist her? Also how early will she show signs of being pregnant?

Answer
Dear Ashley,

Give the mice time to mate.  They haven't gotten to know each other yet.  Mating is always accompanied by a lot of chasing and squeaking, partly because mice just do that when they get to know each other, and partly because girl mice don't like mating.  The male even bites the female's ear to keep her from escaping.  It's normal for her to run.

Although mice often enough come from the pet store already pregnant, a pregnant mouse wouldn't smell 'sexy' to a male mouse and he should have no interest in mating with her.  Female mice come into heat only when they are exposed to a male and are not pregnant.

The soon-to-be mom will be pudgy by the end of the second week and within a few days, she will look like she swallowed a pear.  Because mouse litters can be about any size (I have had every number from 1 to 18), the size difference depends greatly upon the size of the litter.

You will not need to assist her at the birth.  Just make sure she isn't disturbed within the last few days of her pregnancy and has nice, soft nesting material in a nice dark nest spot such as a little box, under some cloth, or in a little house from the pet store.  And leave the nest alone for the first few days, preferably not touching the babies until the 7th day.

Best of luck.  There are a lot of pregnancy related questions in my archives ('see past answers'), so you should be able to find answers to many other concerns you may have.  Feel free to ask more questions as well.

squeaks n giggles,

Natasha