| December year | Under 20 years | 20-24 years | 25-29 years | 30-34 years | 35-39 years | 40-44 years | 45 years and over |
| 1962 | 8.2 | 33.8 | 28.5 | 17.7 | 8.9 | 2.7 | 0.2 |
| 1963 | 9.4 | 33.9 | 28 | 17.1 | 8.8 | 2.6 | 0.2 |
| 1964 | 10.3 | 34.1 | 27.9 | 16.2 | 8.6 | 2.7 | 0.2 |
| 1965 | 11.5 | 34.8 | 28.3 | 14.8 | 8 | 2.6 | 0.2 |
| 1966 | 12.9 | 34.7 | 28.9 | 13.7 | 7.4 | 2.3 | 0.2 |
| 1967 | 13.3 | 35.1 | 29.8 | 13 | 6.6 | 2.1 | 0.2 |
| 1968 | 13.1 | 36.5 | 29.5 | 12.9 | 6.1 | 1.9 | 0.2 |
| 1969 | 12.9 | 36.7 | 29.5 | 13.2 | 5.8 | 1.8 | 0.1 |
| 1970 | 13.2 | 37.6 | 29.3 | 12.9 | 5.4 | 1.6 | 0.1 |
| 1971 | 13.7 | 37.6 | 29.2 | 13.3 | 4.7 | 1.5 | 0.1 |
| 1972 | 14.5 | 36.9 | 29.7 | 12.8 | 4.7 | 1.3 | 0.1 |
| 1973 | 14.5 | 36.1 | 31.2 | 12.6 | 4.3 | 1.2 | 0.1 |
| 1974 | 14.5 | 36.1 | 32.2 | 12.2 | 4 | 1 | 0.1 |
| 1975 | 14.1 | 35.4 | 33.7 | 12.1 | 3.7 | 0.9 | 0.1 |
| 1976 | 13.6 | 35.3 | 34 | 12.5 | 3.7 | 0.8 | 0.1 |
| 1977 | 13.3 | 34.3 | 34.4 | 13.4 | 3.7 | 0.9 | 0 |
| 1978 | 13.2 | 33.6 | 34 | 14.5 | 3.9 | 0.8 | 0.1 |
| 1979 | 12.2 | 32.6 | 35 | 15.5 | 3.9 | 0.7 | 0.1 |
| 1980 | 11.7 | 32.9 | 34.6 | 16.1 | 4 | 0.7 | 0.1 |
| 1981 | 11.3 | 32.5 | 35.1 | 16.5 | 3.9 | 0.7 | 0 |
| 1982 | 10.2 | 31.6 | 36 | 17 | 4.4 | 0.7 | 0.1 |
| 1983 | 9.5 | 31.2 | 36.4 | 17.6 | 4.5 | 0.7 | 0 |
| 1984 | 8.7 | 29.8 | 37.4 | 18.4 | 4.9 | 0.8 | 0 |
| 1985 | 8.8 | 28.8 | 37.3 | 19.2 | 5.1 | 0.7 | 0 |
| 1986 | 8.5 | 27.7 | 37.1 | 20.4 | 5.5 | 0.7 | 0 |
| 1987 | 8.7 | 26.1 | 37 | 21.4 | 5.9 | 0.8 | 0 |
| 1988 | 8.3 | 25 | 36.8 | 22.5 | 6.4 | 0.9 | 0.1 |
| 1989 | 8.6 | 24.1 | 36.4 | 23.3 | 6.6 | 1 | 0.1 |
| 1990 | 8.4 | 23.2 | 35.3 | 24.6 | 7.5 | 1 | 0 |
| 1991 | 8.2 | 23.1 | 34 | 25.3 | 8.2 | 1.2 | 0 |
| 1992 | 7.8 | 22.6 | 32.7 | 26.8 | 8.8 | 1.3 | 0.1 |
| 1993 | 7.5 | 22.2 | 31.9 | 27.7 | 9.3 | 1.3 | 0.1 |
| 1994 | 7.3 | 21.3 | 31.3 | 28.3 | 10.1 | 1.5 | 0.1 |
| 1995 | 7.7 | 20.7 | 30.6 | 28.4 | 10.9 | 1.6 | 0.1 |
| 1996 | 7.7 | 19.9 | 30.4 | 28.4 | 11.7 | 1.9 | 0.1 |
| 1997 | 7.6 | 18.8 | 29.7 | 28.9 | 12.8 | 2.1 | 0.1 |
| 1998 | 7.1 | 18 | 29.2 | 29.6 | 13.8 | 2.2 | 0.1 |
| 1999 | 6.8 | 17.6 | 28.8 | 29.9 | 14.4 | 2.4 | 0.1 |
| 2000 | 6.7 | 17.5 | 27.8 | 30.3 | 14.9 | 2.6 | 0.1 |
| 2001 | 6.8 | 17.5 | 27.1 | 30.5 | 15.3 | 2.8 | 0.1 |
| 2002 | 6.7 | 17.1 | 25.4 | 31.3 | 16 | 3.2 | 0.1 |
| 2003 | 6.7 | 16.9 | 24.9 | 31.2 | 16.6 | 3.5 | 0.2 |
| 2004 | 7 | 17.2 | 24.2 | 31.5 | 16.5 | 3.5 | 0.2 |
| 2005 | 7.2 | 16.8 | 23.9 | 31.1 | 17.4 | 3.5 | 0.2 |
| 2006 | 7.4 | 17.4 | 23.8 | 30.2 | 17.6 | 3.5 | 0.2 |
| 2007 | 7.7 | 17.3 | 24.2 | 28.9 | 18.1 | 3.5 | 0.2 |
| 2008 | 8.1 | 17.9 | 24.3 | 27.7 | 18.4 | 3.5 | 0.2 |
| 2009 | 7.5 | 18.4 | 24.5 | 27.7 | 18.1 | 3.8 | 0.2 |
| 2010 | 7.1 | 18.5 | 24.9 | 27.7 | 17.7 | 3.9 | 0.2 |
| 2011 | 6.5 | 18.6 | 25.1 | 28 | 17.7 | 3.9 | 0.2 |
| 2012 | 6.2 | 18.5 | 25.5 | 28.6 | 17 | 4.1 | 0.2 |
| 2013 | 5.6 | 18.2 | 26 | 28.5 | 17.2 | 4.2 | 0.2 |
| 2014 | 5.1 | 17.3 | 26.6 | 30 | 16.7 | 4.1 | 0.2 |
| 2015 | 4.7 | 17.1 | 26.8 | 30.5 | 16.8 | 3.9 | 0.3 |
| 2016 | 4.2 | 16.2 | 27.5 | 31.2 | 16.8 | 3.8 | 0.2 |
| 2017 | 3.9 | 15.7 | 28.1 | 31.5 | 16.7 | 3.8 | 0.3 |
| 2018 | 3.6 | 15 | 28 | 32.2 | 17.3 | 3.7 | 0.3 |
| 2019 | 3.3 | 14.3 | 27.5 | 33.1 | 17.7 | 3.8 | 0.3 |
| 2020 | 3.3 | 13.9 | 27.3 | 33.9 | 17.8 | 3.6 | 0.3 |
| 2021 | 2.7 | 12.9 | 26.7 | 35.5 | 18.4 | 3.6 | 0.2 |
| 2022 | 2.9 | 13 | 25.8 | 35.4 | 18.8 | 3.8 | 0.2 |
| 2023 | 3.1 | 12.8 | 25.2 | 35.5 | 19.2 | 3.9 | 0.2 |
| 2024 | 2.9 | 12.2 | 24.2 | 36.1 | 20.3 | 4 | 0.2 |
| 2025 | 2.7 | 11.6 | 24.1 | 35.6 | 21.5 | 4.2 | 0.3 |
Proportion of births to mothers aged under 25 drops in all regions
Every region in New Zealand had a decrease in the proportion of births to mothers aged under 25 years between 1995 and 2025. The Bay of Plenty had the largest decrease, dropping from 37 percent of births in 1995 (the highest proportion of all regions that year) to 18 percent in 2025.
In 2025, 1 in 4 births in the Gisborne region were to younger mothers (25 percent), the highest proportion across the regions that year. In contrast, Otago, with around 1 in 12 births to younger mothers, had the lowest proportion in 2025 (8 percent).
In 1995, Gisborne was also amongst the regions with the highest proportions of younger mothers: along with Hawke's Bay, it had 36 percent of births to mothers aged under 25 years. Hawke's Bay also remains a region with a higher proportion of younger mothers in 2025 (21 percent).
Otago had one of the lowest proportions of births to younger mothers in both 1995 and 2025, however the proportion in 1995 (24 percent) was much higher than in 2025 (8 percent). The only region with a lower proportion than Otago in 1995 was Canterbury (23 percent).
"Regions such as Otago which have a higher proportion of their population studying are expected to have lower proportions of younger mothers," Watkins said.
"With exceptions like Otago, the number of births to women at different ages will be influenced by the number of women of those ages in the population. Birth rates published in May last year help understand this."
| Region | 1995 | 2025 |
| Gisborne | 36.1 | 24.8 |
| Hawke's Bay | 36.4 | 20.8 |
| Manawatū-Whanganui | 33.2 | 20.8 |
| Northland | 34.7 | 20.4 |
| Southland | 31.9 | 19.1 |
| Taranaki | 31.9 | 18.4 |
| Bay of Plenty | 37.3 | 17.9 |
| Waikato | 33.5 | 17.9 |
| Nelson | 26.0 | 15.0 |
| Marlborough | 27.1 | 14.0 |
| West Coast | 28.7 | 13.7 |
| Auckland | 25.3 | 12.5 |
| Wellington | 25.0 | 11.9 |
| Canterbury | 22.9 | 9.9 |
| Tasman | 24.1 | 9.3 |
| Otago | 23.6 | 8.1 |
Proportion of older mothers increases in all regions
The proportion of live births to mothers aged 35 years or older ('older mothers') in New Zealand doubled from 13 percent in 1995 to 26 percent in 2025.
"Every region in New Zealand has had an increase in the proportion of older mothers between 1995 and 2025," Watkins said.
In 2025, the Wellington region had the highest proportion of births to older mothers, with nearly 1 in 3 births to mothers aged 35 or older (31 percent). This compares with 15 percent of births in 1995. Wellington, Auckland, and Nelson (both also 15 percent) were the regions with the highest proportion of older mothers in 1995.
Gisborne and Taranaki had the lowest proportions of births to older mothers in 2025 (18 and 19 percent respectively), up from 10 percent of births in 1995.
| Region | 1995 | 2025 |
| Wellington | 15.0 | 30.5 |
| Nelson | 15.4 | 29.4 |
| Otago | 12.4 | 29.1 |
| Tasman | 12.0 | 28.5 |
| Auckland | 14.6 | 28.4 |
| Canterbury | 13.3 | 27.3 |
| Marlborough | 10.5 | 26.2 |
| West Coast | 10.8 | 24.2 |
| Hawke's Bay | 10.4 | 23.3 |
| Bay of Plenty | 9.7 | 21.9 |
| Waikato | 10.0 | 21.9 |
| Northland | 10.9 | 21.6 |
| Manawatū-Whanganui | 10.1 | 20.1 |
| Southland | 9.5 | 19.9 |
| Taranaki | 10.0 | 18.6 |
| Gisborne | 10.3 | 18.4 |
