....so she had a reason for being so big A 16 mouse litter is really good...IMO. I usually average around 12 but I have had up to 15 before. I would definately keep back a few of the larger female babies and see if they have litters like their mama The litters do tend to get larger, but I doubt they will get any larger than 16.....when there are more babies than that a single mother might have trouble careing for them all. Thats why I always make sure I have two female per enclosure when baby time arrives....they are pretty good at helping each other out