The Government aims to have at least 500 Sure Start programmes running in deprived wards by 2004. They offer health support and education for under-fours and their parents. Next week it will announce plans to re-brand the centres, and its Early Excellence projects, as "Children's Centres".
But US research found that the American Head Start programme, which inspired Sure Start, had only a short-term effect on toddlers.
Professor Richard Pring of Oxford University said the US scheme gave cause for pessimism: "The studies suggest that they are a good thing for the short term, but by the time people come to leave school, go on to secondary school, the impact has dissipated."
Early years minister Baroness Cathy Ashton was quizzed about the US findings this week by the Commons education select committee. Committee chairman Barry Sheerman said it was worrying that so much "national treasure" was being put in Sure Start.
But Baroness Ashton replied that the evidence from the US scheme had been mixed and that children in the UK were more likely to achieve what they were capable of if they attended Sure Start.