Sounds exactly like the title to a fantasy novel, doesn't it? BUT, it isn't. No, no, I decided to do some Googling after seeing this post* on Tumblr. Someone mentioned that Mexico once had a president who only served for forty-five days and for whatever reason, I got the idea in my head to find out who the youngest monarch ever was. Yeah, I don't know how I made that jump either. In any case, my Google-Fu was on point tonight and I found this post on Mental Floss listing just what I was looking for, and that's how I found out about an unborn king named Shapur II and holy hell, this guy's story is a doozy.
Basically, his dad, Shapur I died before he was born and Persian nobles, for whatever reason, blinded one brother, killed another, and imprisoned the last one, clearing the path for Shapur to take the throne as the ninth king of the Sassanid Empire. Apparently him still being in the womb wasn't an issue to these nobles and they crowned him before he was even born. He would go on to rule for seventy years and did well enough at the job to be given "The Great" appended to his name. I tell ya, history is both awesome and weird as hell, man.
*Fair warning, my Tumblr is NSFW, so use caution if you decide to go exploring.