The number of women under the age of 20 giving birth has dropped significantly in the last 20 years, figures from the Central Statistics Office have shown.
CSO figures showed 3.7 live births per 1,000 women aged under 20 in Ireland last year, compared with 17.6 live births in 2004.
This represents a 79% decrease.
The number of births by women under 20 in 2004 was 2,560.
Last year that number was down to 634.
Meanwhile, the number of live births by women aged 45 or over was 461 last year, an increase from 78 in 2004.
The CSO figures also show that the average age for a first-time mother was 31.7 last year.
This is an increase from 2014, when the average age was 30.5, and 2004, which was 28.5 years old.
There were 54,062 live births last year, a drop from the 2004 figure of 61,684.
There was also a recorded decrease in the 20-24, 25-29 and 30-34 age groups over the same period.
The number of births in the 20-24 age group last year was 3,886, down from 8,213 in 2004.
In the 25-29 age group, the number decreased from 14,339 in 2004 to 9,088 in 2024.
The 30-34 age group saw a slight decrease over the last 20 years, dropping from 21,267 to 18,773.
Dr Carmel Hannan, Associate Professor of Sociology at University of Limerick, said the latest CSO figures are part of a long-term trend and a global issue.
"They reflect women postponing having children and getting married. This is a big global issue so countries all over the world are talking about this."
She said it is related to several other changes also in Irish society.
"Women are significantly more likely to be in the labour market and educational system. In fact, women have surpassed men in terms of third-level education. They are also more likely to be in the labour force. So, all of these are leading to postponement in long-term decisions."
She said there is an increase too in "risks" to young people's lives which delay them having children, including home ownership.
She said other data has shown that among 25-year-olds "a staggering 69%" are still living at home with their parents.
She said in this context it is hard to see how people can make long-term decisions.
She said there are " very divergent trends" between those who wait and those who have children at a younger age.
She said the latest CSO statistics show Ireland has followed other countries with a declining population.
"In some ways you could argue that is a good thing, there are too many people on the planet. But actually from a societal and economic point of view we do need to address this issue."
Dr Hannan said it has serious consequences for pensions and care.
