The rule was and still is that the birth can be registered "by the occupier of the house or hospital where the child was born", hence the use of the terminology. A doctor's signature would be followed by the letters of his/her medical degree, however, it it more likely to be a member of what would now be called the administrative staff. I have a death certificate from a London hospital (1873) with the signature of the occupier whose official title (not on the certificate), was Steward of the Hospital (a mediaeval title probably peculiar to that ancient foundation). The current responsibilities of the office are public relations, legal claims, and general administrative care of patients and their relatives. MAR in France.