no babies/ too many mice

Question
I have four separate cages, each cage has one male and three female mice. i have had them all together for about six weeks now and i have not had even one litter. i keep food and water in the cages at all times, and i keep them at a pretty consistent temperature of 75, i also give them 12 hours of light and dark. i don't understand what i am doing wrong. please help!!

Answer
Dear Noelle,

The temperature should be a little lower than that.  My mice appreciate about 72 degrees; when it is 75 degrees they lie out on their wood chips like little puddles.  They don't need 12 hours of dark; the normal seasonal time is fine for them. And I recommend only two females per cage with one male.

How old were they when you got them? Males, and sometimes females, are not mature enough to mate until they are 6 weeks old. Then females come into heat about every 3-5 days.  Are you also sure it has been 6 weeks since you got them (and they were old enough)? And none of them are fat?  

Although you haven't had any babies so far, once they start mating, three weeks later you are at risk of having 12 litters of mice at 8-12 babies each, making about 120 babies at once. Are you sure you want that? Three weeks later you would get another 120. The first 120 babies will start to mate 6 weeks  later (the girls 4 1/2 weeks  later, if Dad is still in the cage, but let's assume 6). At 9 weeks after the first birth, you will already have 376 (120 + 120 + 120 + the original 16) mice. At that point,  the 12 original adults will give birth to another total of 120 pups, and the 120 first generation babies will give birth to (60 females X 10 babies each) 600 pups. That makes 1096 mice only 3  months after they first mate. Are you sure you know what you are getting into?

squeaks and giggles,

Natasha