My wife and I are looking to book LGA-CVG mid-June for a wedding. My wife is pregnant and while at her obstetrician today, we asked him if she'd be able to fly then. He said that it would be the borderline time and that we could book the tickets figuring that if worse came to worse, he'd give us a note to cancel the tickets with. I didn't question him, but have never heard of a doctor's note to cancel air travel. Sounds kinda weird to me. Is there such a thing?