The basic intent of POB advice is so that rescue services know how many persons to recover after an accident. Thus, POB count is, as
hvogt has pointed out, includes all LIVING persons on board, passengers and crew.
When I was with the Flying Doctor, I once advised upon taxy 6 POB, being myself, 3 medical staff, one dying patient, and one in advanced labour.
En-route, sadly, one patient died, and I duly advised Flight Service of amended POB 5. A little later, the pregnant patient delivered her baby, and I duly advised Flight Service of amended POB 6.
The predictable reply from Flight Service was "Make up your mind!"
Regards,
Old Smokey