David Cameron said Labour had failed the poorest in society
The Tories have been attacked as "out of touch" for wrongly claiming more than half of girls in the most deprived areas get pregnant before they turn 18.
The party said the conception rate for this age group in the 10 most disadvantaged areas of England was 54%, while the real figure was 5.4%.
Labour accused the Conservatives of using "smears and distortions".
But the Tories said the misplacing of a decimal point made "no difference" to claims Labour had let down the poor.
The pregnancy figure was given in a 20-page dossier, published on Sunday, attacking the government for allowing the creation of "two nations" - the wealthy and the impoverished.
In response, Labour said the correct figure of 5.4% represented a fall from 6% in 1998.
Children's Secretary Ed Balls said the "dodgy" figures were an insult to communities and called on the Tories to withdraw the document.
He said: "David Cameron's latest deception and airbrushed statistics cannot conceal the fact that the Tories haven't changed.
"They are totally out of touch and have nothing to say on the important issue of reducing teenage pregnancies except smears and distortions."
House of Commons leader Harriet Harman told the BBC: "You would have thought that someone [in the Conservative Party] would have thought 'Surely there's something wrong about this'.
"They are so out of touch. Someone junior made a mistake and no-one picked it up."
The Liberal Democrats' chief of staff, Danny Alexander, said: "The Tories seem to think that half our teenagers are pregnant, our cities are like The Wire and that people will get married for a few extra quid.
"If they really believe Britain is like this, it's remarkable that Conservative MPs can pluck up the courage to leave their houses.
"They should lower their drawbridges, spend less time tending their moats and duck houses, and join the rest of us in the real world."
But a Conservative Party spokesman said: "A decimal point was left out in a calculation.
"It makes no difference at all to the conclusions of a wide-ranging report which shows that Labour have consistently let down the poorest in Britain."
On Monday Tory leader Mr Cameron and party chairman Eric Pickles launched a poster campaign designed to reach out to voters who would not usually vote Conservative.
In the foreword to the "Two Nations" document, Mr Cameron said: "Labour's great claim is that they are 'for the many, not the few'.
"That rings hollow today. This report exposes the truth: after 13 years in government, the party that prides itself on fairness has delivered the very opposite. Labour have failed the poorest in our society."