Because she was married to a British citizen, it would be very easy for her to go to any Canadian hospital at that time. There are towns like White rock that are very close to the border.
I realize that and Vancouver area at that time didn’t suffer from the racial tensions that were prevalent in Seattle area. Also travel across the border was extremely easy at the time I experienced it myself. The border guard would ask for a driver’s license of the driver and ignore any passengers. There was also a home for unwed mothers in Vancouver very near Vancouver General Hospital which was run by the Salvation Army. Contact between mothers and babies was discouraged in these homes which could explain why Ann didn’t know how to change diapers.