Last year, for the first time ever, there were more births to women aged 35 and over than to those under 25 in England and Wales.
In 2014, 21% of babies were born to mothers aged 35 and over. That compares to 20% of babies whose mothers were aged 25 and under.
The new data, released by the Office for National Statistics, shows there were 144,181 live births to women aged 35 and over, and 138,592 to women under 25.
Over half (52%) of all live births were to mothers aged 30 and over, while two-thirds (67%) of fathers were aged 30 and over. Babies were most likely to have a mother aged 25 to 34, with 59% of mothers in this age group.
The average age of mothers at the time of giving birth was 30.2 years in 2014 – compared to 30.0 in 2013. The average age of fathers was 33.1 years, up from 32.9 years.
Here's how the age of mothers has changed since 1938.
The number of babies born to women aged 35 and over dropped to a low of 31,515 in 1977. It has steadily been rising since then but has still not yet reached its peak of 149,046 in 1947.
Meanwhile the number of babies born to women aged under 25 has fallen dramatically from a peak of 378,021 in 1968.
The ONS said the overall rise in the average age of the mother since 1975 reflected the "increasing numbers of women who have been delaying childbearing to later ages".
It said factors could include more women going to university, the increasing importance of a career, the rising costs of childbearing, the uncertainty of the labour market, housing problems, and "instability of partnerships".
This is how the age of new mothers and fathers compared in 2014.
The data shows that fathers tend to be older than mothers. While 16.2% of live births were to women aged 20 to 24, only 9.9% were to fathers in the same age bracket.
At the other end of the scale, 16.6% of babies were born to women aged 35 to 39 – compared to 21.5% of fathers in the same age range. And 3.9% of live births were to mothers aged 40 to 44, compared to 10.1% for fathers.
Here's the partnership status of new parents in 1986, 2004, and 2014.
Marriage or civil partnership remains the most common family setup for births in England and Wales. But there has been a steady fall in the percentage of births registered to married couples since the 1960s.
In 2014 just over half of births (53%) occurred within marriage or civil partnership, compared with 58% in 2004 and 93% in 1964.
Some 84% of births were to parents who were married, in a civil partnership, or co-habiting. Another 10% of births were registered jointly by parents living at separate addresses, while only 5.4% were registered by the mother alone.
And this is how the partnership status changes, depending on the mother's age group.
Some 96% of women aged under 20 who gave birth in 2014 were not married or in civil partnerships. Births to mothers aged under 25 were most likely to be jointly registered by co-habiting parents.
In contrast, the majority of new mothers aged 30–34 and 35–39 were either married or in a civil partnership.
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Emily Ashton is a senior political correspondent for BuzzFeed News and is based in London.
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