Living at the convent makes a certain kind of sense on several levels:
a. The nurses don't have big salaries, but if "room and board" are included, the pay won't be a huge issue.
b. In a time where not everyone had a phone, and pagers were non-existent, a common phone in the house means the midwives could respond quickly to any emergency.
c. Meals in common, trading stories and updates about cases, and you still get to date? Much better than a boarding house.