The number of children in England's primary and nursery schools is set to soar by 18% in the next eight years, official figures show.
By 2020, the numbers are expected to reach levels last seen in the 1970s, according to data published by the Department for Education (DfE).
The latest figures reveal that there are currently 4,114,000 children in England's primary and nursery schools. By 2020, this is projected to rise to 4,850,000 - a rise of 18%.
Between 2012 and 2015 alone, pupil numbers in these schools are predicted to increase by 8%, the statistics show.
At the same time, pupil numbers in secondary schools are expected to fall until 2015, when they will start to rise as primary-age pupils move up.
The hike in primary and nursery school pupils has been fuelled by an increasing birth rate, which has been broadly rising since 2002 and is predicted to continue to do so until 2014.
Projections produced by the Office for National Statistics (ONS) show that some regions will be feeling a squeeze on places more than others.
While all areas are set to see an increase in their primary age population, it will range from a rise of around 9% in the north east and south west, to an 18% rise in London.
Schools Minister Lord Hill said that the Government is taking action by spending more than £4 billion on extra primary school places.
"The last Government knew there was an issue as early as 2004, but sadly did nothing," he said.
"Worse than that, they actually cut funding for new places while squandering millions on expensive secondary schools."