The birth rate has gone up by 2% from a year ago, with nearly 64,000 babies being born.
Demographers are unsure of the reason for the increase.
Statistics New Zealand says 2010 might simply have been a year in which couples wanted to complete their families.
Multiple births have remained at 15 pregnancies per 1000, after peaking at 17 in 2002.
Treatment provider Fertility Associates says the decline in that area shows a Government cut to funding for multiple embryo transfers is working.
The average age to become a first-time mother is still 30.
Twenty-six women under the age of 15 had children in 2010 and more than 130 babies were born to women over the age of 45.