There have been manly men called Fran, like football great Fran Tarkenton and Hannah's boyfriend in one season of Girls, but that doesn't mean it works for babies anymore of either gender. Pope Francis may have inspired many little namesakes, but they're called Francis or Frances or Francesca....or maybe Frank or Frankie or Franny. Not Fran.

This short form has been pretty much replaced by Franny, Fanny. and especially Frankie.