The Campaign to End Child Poverty published figures today showing that 20.2% of British children are classified as below the poverty line before housing costs.
In eight areas of large cities, over four out of every 10 children lived in poverty in 2012, the research showed.
But that is a decrease on the 19 parliamentary constituencies that had 40% of children living in poverty in 2011.
The poorest constituency for children was Manchester Central, with nearly half (47%) of children living in poverty.
Over four in 10 children were living in poverty in Belfast West (43%), Glasgow North East (43%), Ladywood, Birmingham (42%), Liverpool Riverside (42%), and Middlesbrough (40%).
In London, 40% of children were living in poverty in Tower Hamlets, 42% of children were below the poverty line in the constituency of Bethnal Green and Bow while 41% were living in poverty in Poplar and Limehouse.
The situation has broadly improved since 2011, except in some areas of the North East of England.
In Newcastle, 38% of children were poor in 2012, compared with 29% in 2011, while in Middlesbrough the figure rose to 40% from 38% in the previous year.
Child poverty was the lowest in Deputy Prime Minister Nick Clegg's Sheffield Hallam constituency (below 5%). It was also under 10% in Prime Minister David Cameron's Witney constituency, the report said.