And I thought she was a boy soooo...its pretty surprising. When we got the mice we got 2 boys and a girl (oops). One died not long after we got them and I thought it was the girl. The last week, another escaped. My mom went to say hi to the mouse yesterday and she thought Mousey (yes, we have original names) looked fat/pregnant. According to the internet, mouse gestation periods are 21 days and they can start showing around 8 days. They start looking somewhat pear shaped or like they ate a golf ball. Mouse baby daddy got her pregnant then left?? Its possible. So, I gave her papertowel to tear up and use as nesting material - the internet said they like that too. Aaaand in a week or two, depending on how far along she is, we'll see if babies do appear.