Oddly specific question but I am curious if there are any historical precedents for this kind of event.
Would they wait for the child to be born? Is the child completely left out of succession when he is born?
Also assuming the monarch has no children aside from the unborn child.
I am curious if there are any historical precedents for this kind of event.
From the Middle Ages, yes. Here's a previous post from u/sunagainstgold, examining three cases of posthumous children. Further insight is always welcome from anyone with the knowledge to contribute!
"The Middle Ages love you, and want you to be happy." - u/sunagainstgold