Quoting Jensens_Girl:" Is it common in the US for an OB to take on someone thats due at the time they'll be on holiday? Why ... [snip!] ... the LMC (lead maternity carer) that you choose is going to be away at the time of your due date they dont take you on..."
Doctor's have lives, too. They always have patients in their care. Always. They would never get a break or vacation if they saw every single one of them through. They almost always have associates or partners they trust and leave their patients to. So, while it sucks for some women...I'd rather them vacation or whatever and not get burned out on work.