It's a good point that I think people forget or overlook (and I say this as someone who has worked with people who had lots of medical debts in the US - not as someone who has given birth) - is like what Marlespo is saying about its being never ending. It's not just one bill - it's lots & lots & lots of bills: for the hospital bed, for the medicines - aspirin & prescriptions, for each doctor, each specialist, each test, each diagnostic, having tests/diagnostics read or interpreted, each technician, on & on & on & on. Imagine someone who cannot afford to pay all that or who doesn't have insurance, then each bill gets referred on to a collection agency and then the next collection agency and the next and the next. It's no wonder that I used to have clients arrive with grocery bags full of unopened post, because they were getting so many different bills they just couldn't face opening their mail anymore - didn't know who was collecting for what, etc. Not good. When I have explained this to friends, family & colleagues here in the UK, their jaws just drop open - unable to fathom such a system.
Compared to the NHS where you never see a bill & if you have to pay for a prescription (which I don't think you do for pregnancy stuff?) - it's £7.50.