
I agree white lilly. But then, even with a large breed I wouldn't expect to leave a bitch 12 days, and it's got to be remembered that novices will read this board, and may think that being overdue is normal, so not getting veterinary advice when needed.
I had heart failure when I read 12 days - I knew a silly terrier owner that left her bitch 7 days over before doing anything. Eventually, a vet visit found a decomposing puppy in the birth canal. So I would always, always recommend that any newbie breeder acted on the side of caution.