"I often wonder about the souls of the unborn, and yet-to-be conceived, in the rapture.
"How do souls work? Is there a finite number of souls? How many souls will there be, from start to finish?
"If the rapture comes today, what of all the souls the souls that could have been here, had the rapture came tomorrow instead?
"What about pregnant women, how will their unborn children be judged; what if the mother had not accepted Christ, will the child suffer for the mistake of the parent?
"I hope the rapture comes in my lifetime, just so I can get some answers! :P"
To begin, the yet-to-be conceived won't be conceived until after the Tribulation. There are references to children in the Millennial Kingdom in Tanakh. I sadly don't have these references off hand or memorized, however. When I find them again sometime (if the Rapture doesn't come before I can find them again), I'll (G-d willing) post them in another entry.
As for unborn children, they-- since they haven't reached the age of accountability-- will, sadly for the mothers who are unsaved, be taken straight out of the womb and raptured in Heaven while the unsaved mothers are left behind and (in regards to their unborn children) childless. As far as Tanakh indicates, the soul isn't even created until during or after conception; so as I said, any yet-to-be-created souls will be created after the Tribulation whereas already-created souls will be (with the bodies that hold them) be raptured.
I hope that this answers your question, Charles.