The number of babies arriving in England and Wales fell last year in the steepest drop since 1975.
Births numbered 698,512 in 2013, a fall of 4.3%, according to the Office for National Statistics.
A woman’s average number of children decreased from 1.94 to 1.85.
The average age of mothers jumped up as well, standing at 30 last year compared to 29.8 years in 2012.
It was the first time for the average age to be 30 since records began in 1938, although it has been gradually creeping up since 1975, and is one of the highest in the world.
There was also an increase in the number of births to mothers who were born outside of the UK. The percentage was 26.5%, up from 25.9% the year before.
Prior to 2013, the trend had been for increasing number of births since 2001, with the exception of a slight dip in 2009.
The ONSW report said reasons for the decrease in fertility rates could include uncertainty over employment and career opportunities, and government changes to the welfare system affecting benefits.
Nearly half of all babies (47.4%) were born outside marriage or civil partnership in 2013. The ONS said this continued a rising trend, with the figure 41.4% in 2003.
