Wizard asked an excellent question in the comments section and I thought it bore a full post:
How did a priest get to be the patron saint of Mothers:
Our answer from Terry Jones at Saints.SQPN.com
When falsely accused by a pregnant woman of being the father of her child, he retreated to silence; she later recanted and cleared him, and thus began his association as patron of all aspects of pregnancy. Reputed to bilocate and read consciences. His last will consisted of the following small note on the door of his cell: “Here the will of God is done, as God wills, and as long as God wills.”
Interesting. We’re a kooky church sometimes, but this is a great story nonetheless.