WELLINGTON, Feb. 19 (Xinhua) -- New Zealand's total fertility rate in 2017 was down to 1.81 births per woman, its lowest recorded level, the country's statistics department Stats NZ said on Monday.

This means that based on birth rates in 2017, New Zealand women would average 1.81 births over their lifetime, which was similar to Australia's rate of 1.79 in its latest data in 2016, Stats NZ said.

Although the number of births increased slightly, which were 59,610 live births registered in 2017, up 180 from 2016, the fertility rate still decreased. This related to the increased population size rather than fewer babies being born, it said.

"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 in a statement.

The lower fertility rate may lead to reduced population growth if it stays below the "replacement level" of approximately 2.1. The replacement level reflects the average number of babies that women would need to have over their lifetime to maintain the size of the population, Dolan said.

The total fertility rate has only dropped below 1.9 births three times before, most recently to 1.87 in 2016, he said, adding that New Zealand's total fertility rate has been relatively stable for the last four decades, ranging from 1.81 births per woman in 2017 to 2.19 in 2008.

"In contrast, fertility rates increased dramatically following the Great Depression and World War II, peaking at 4.31 births per woman in 1961," Dolan said, adding that New Zealand then experienced declining fertility over the following two decades.