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
Jay Oxley was diagnosed with a rare form of cancer and had to be put into a coma.
UKIP leader Paul Nuttall is set to contest the Stoke Central by-election later this year according to ITV Central's Political Correspondent
Jeremy Corbyn has accused Theresa May of producing a "bargain basement Brexit" plan and "demeaning" the UK's European standing.