The first nine months of the year produced the highest number of recorded births since 1962 - when New Zealand mothers averaged over four children each.
Statistics NZ data showed there were 64,450 live births in the year to September, the highest since 1962 (65,660) when the population was 42 percent lower than the current 4.3 million.
Statistics show the birth rate in the year to September 2008 reached 2.2 per woman - up from 2.1 in the corresponding period last year, but way down compared to the 1960s.
The figures put the median age of women having children at 30, compared to 25 in 1968.
The highest fertility rate was from women aged between 30 and 34, (127 births per 1000) whereas 40 years ago it was from those aged 20 to 24 (218 births per 1000).
Meanwhile, there were 29,130 deaths registered in the year to September.
The statistics showed the median age for those deaths was 77 for males and 83 for females, compared to 72 and 77 in 1988.
Births exceeded deaths by 35,410 up to September, but national population projections show that natural increase is likely to decline over the next 50 years and deaths are predicted to outnumber births from 2055.
NZPA