From today, women in labour in Auckland need to go to Auckland City Hospital in Grafton, not National Women's in Epsom.
A birthing suite will remain open at National Women's until 7pm while the transfer of services takes place.
Auckland City Hospital manager Nigel Murray said having birthing, maternity, newbornand gynaecology in-patient services in the new hospital provided patients with access to a wide range of specialist services.
Patients requiring specialist care would not have to be transferred across town or between hospitals.
The new facility, on Level 9 of the main building, is called National Women's Health in Auckland City Hospital.
Women in labour will be able to press a priority button on lifts to allow them quick access to delivery suites.
Most outpatient services and Fertility Plus will remain at their current premises in Greenlane before transferring into a new Greenlane clinical centre early next year.
National Women's Hospital opened in February 1964. More than 250,000 babies have been born there.
The building will become offices for the Auckland District Health Board.
