The Government says council planners may have to go back to their drawing boards, based on new figures showing the country's population growth has dramatically slowed.
Data from the latest census shows the population has grown by about 31,000 people a year since 2006, compared with 58,000 a year for the five years before that.
Statistics Minister Maurice Williamson says he was startled by the much lower than expected population growth.
He says it will throw a spanner in the works for councils which have been making plans based on the historical rate.
Local Government New Zealand agrees councils will have to take note of the new figures but says their plans are unlikely to change dramatically because they're based on figures over 10 or 15 years.
A political analyst says it could take years before the Christchurch electorates settle down after the earthquakes.
All but one of the city's electorates look set to have their boundaries changed due to shifts in the population.
Census data shows Christchurch East has lost 10,000 people while seats surrounding the city have had gains.
Canterbury University senior lecturer in politics Bronwyn Hayward says it's likely to take another two election cycles before the seats stabilise.
Dr Hayward says the Labour Party will most likely be hit the hardest because many of its traditional supporters, including those on low incomes, who are likely to have left the city for good.
