Young women who have dogs are more likely to have children eventually than young women who have cats.
Among my acquaintances it's more true than not, & it makes sense: dogs require more attention & care, so women who are willing to take care of a dog are primed for kids.
I have no idea if this is true, or what it means.
Update: My brother just pointed out that some people have dogs [& cats?] in lieu of kids.