KatiePul Congratulations on the pregnancy. Normally, I would always say that it is up to the parents to choose the name and in this case too I agree it is your choice. I think, personally, that your mother will come around in time.
However, just as an aside, I think that the name ?Fox? could prove problematic for your little one. Certainly, as a first name it might make some things harder, like introducing himself at school or later in life. Would you consider it as a middle name? I only say this because I think kids can have a tough enough time at school without an unusual name.
This is just my personal opinion, I know not everyone will agree with me.
To me ?Fox? sounds cool, so if your child is confident and full of life, he may well ?get away with? an unusual name. But if he is quieter or shyer he may not like standing out. You could always call him ?Fox? whatever is on his birth certificate.
Fox has a few connotations, some positive and some not so.
Whatever you choose to do, I hope that it will be a really joyful time for you and not marred by any arguments or fighting about names.