Almost half of children are born to unmarried parents, figures suggest.
In 2011, 47.2% of the 723,913 babies born in England and Wales were born to parents who were not married or in a civil partnership, the Office for National Statistics (ONS) said.
The ONS statistics also show that during the last two decades, the number of women giving birth in their 40s has trebled.
Last year, 29,350 women aged 40 or over had a baby, compared with just 9,835 in 1991.
The number of women aged 35 to 39 who gave birth in 2011 was 3.4% higher than in 2010.
The ONS said the figures represent a continuation of increasing age of motherhood.
A number of factors could contribute towards delaying motherhood including desire to establish a career, getting on the housing ladder and ensuring financial stability before starting a family, the ONS said.
The figures also provide more evidence that the population in England and Wales is ageing. The number of registered deaths in 2011 fell by 1.8% from 2010.
There were 484,367 deaths last year - the third consecutive year in a row that the number of registered deaths was below half a million.
The ONS said that before 2009, the last time that death registrations fell below 500,0000 was in 1952.