Just under 50% of women are waiting until they reach 30 to give birth, according to the latest figures from the Office for National Statistics.
In 2010, 48% of all infants born were to mothers aged 30 and over, up from 47% in 2009 and 46% in 2000.
The last time so many babies were born to women of this age was after the Second World War, in 1946.
The proportion of mothers under the age of 25 has fallen steadily since its peak in the early Seventies.
More top news
Philip Thomas doesn't like to dwell on the disaster that buried him alive - but he can still recall in detail how an unpaid debt saved him.
The deal would set up a free trade zone between the EU and Canada - and could be an important test for the UK's Brexit negotiations.
A mother has won her battle against the Home Office to allow her Nigerian sister into the country - so she can undergo a marrow transplant.