The UK population increased more last year than at any time in almost half a century, according to figures from the Office for National Statistics.
By mid-2010 the estimated resident population was 62,262,000, an increase of 470,000 (0.8%) on the previous year.
The growth rate is the highest since 1962, during the "baby boom" years.
'Natural change' - the difference between the numbers of births and deaths - accounted for 52% of the population growth.
The number of births in the UK is now at its highest since 1991, with 797,000 during the year to mid-2010.
The Office for National Statistics (ONS) says two factors are significant - rising fertility among UK-born women and more inward migration of women of childbearing age.
'Natural change' has been the main driver of growth for the last three years (2007-10), having narrowly overtaken net migration, which was the dominant factor for the previous nine years.
Net migration - the difference between long term migration into and out of the UK - shows a positive figure of 230,000 for 2009-10.
Overall, the ONS says the UK population has increased by 3.1 million people between 2001 and 2010.
The House of Commons library, in response to a question by James Clappison MP, recently estimated that the figure could exceed 70 million by 2026, three years earlier than previous official estimates.