Birth rate drops to record low since records began

New Zealand's birth rate has dropped to its lowest level since records began in 1920.

There were 59,610 lives births last year, and based on this rate a Kiwi woman would average 1.81 births across her lifetime according to Statistics New Zealand.

"While the fertility rate is now the lowest ever seen, the total New Zealand population continues to grow, driven by near-record levels of migration in 2017," population statistics senior manager Peter Dolan said.

Birth rates for women aged 15-29 are at a record low, the main factor driving the fall since 2008.

Teen births dropped to their lowest level ever, with 15 for every 1,000 women aged 15-19. That's almost half of the 2008 rate of 33 births per 1,000 teen women.

The fertility rate has been relatively stable since 1980, with an annual average of 2.01 births per woman from 1980 - 2017.

The lower fertility rate of 1.81 births per woman could reduce population growth if it stays below the replacement level - the number of babies women need to have over their lifetime to maintain the population size - of approximately 2.1.

The median age for a woman to give birth in 2017 was 30, unchanged since 1999. In the 1970s the median age for women giving birth was 25.

The infant mortality rate in 2017 was 3.9 deaths for every 1,000 live births.