A female can get pregnant a day or so after she gives birth. It is generally 3-4 weeks of pregnancy, then the babies are born. Most people like to give their females a few weeks break between pregnancies to give them a rest. But usually if you time it right you have another litter from a mother about the time her previous litter is adult size(5 weeks).

ha ha....when you have bps that will the 3-4 young adult mice at one sitting...they dont last that long....but are definately cheaper then buying mice from a pet store