11. Regions---(1) For the purposes of this Act, New Zealand shall be
 divided into the following regions:
   (a) The Northern region:
   (b) The Waikato region:
   (c) The Central region:
   (d) The Wellington region:
   (e) The Canterbury region:
   (f) The Southern region.

   (2) Every region shall comprise the hospital districts specified in
 relation to that region in the First Schedule to this Act.

   (3) The Governor-General may from time to time, by Order in Council,
 vary the boundaries of a region by adding or excluding a hospital
 district.

   (4) Where an Order in Council is made under subsection (3) of this
 section varying the boundaries of a region to include a new hospital
 district, the Order in Council may be made with effect retrospectively
 to come into force on the day on which the hospital district is
 constituted.