More babies have been born to women aged 35 and over than to those under 25 for the first time ever.
Office for National Statistics (ONS) data shows that in 2014, 21% of new babies had mothers aged 35 and over compared to 20% whose mothers were aged 25 and under.
There were 138,592 live births to women under 25 and 144,181 to women 35 and over.
Overall, babies were most likely to have a mother aged 25 to 34, with over a half (59%) of mothers in this age group.
The figures, for England and Wales, also show that fathers tend to be older than mothers.
In 2014, two-thirds (67%) of babies had fathers aged 30 and over, while over half (52%) of all live births were to mothers aged 30 and over.
The average age of all fathers increased to 33.1 years in 2014, compared with 32.9 years in 2013.
For mothers, the average age was 30.2 compared with 30.0 in 2013.
The average age of first time mothers was 28.5 years in 2014, compared with 28.3 years in 2013.
And in 2014, just over half of births occurred within marriage or civil partnership (53%), compared with 58% in 2004 and 93% in 1964.