Most people know that mice populations grow rapidly. If you see one mouse, there is a pretty high chance there are more not too far away.
Not only can mice have multiple babies at once, they also can have multiple litters each year. Female house mice can have up to six pups every three weeks and can give birth to a second liter as early as 25 days after the first. In one year, they can give birth to approximately 35 babies. On average humans will only have one baby per year and a total of two in their lifetime, so compared to people, that is a lot of mice!
Mice are born without fur, ears, and the ability to see. Because of this, mothers nurse their babies for 21 days. By the fourth day their ears fully develop, by the tenth day they grow a full coat of hair, and by the fourteenth day they open their eyes for the first time. After 21 days of nursing, the pups will wean and leave their mothers. At two months old, female mice are fully matured and can begin having pups of their own.