For the first time, racial and ethnic minorities account for more than half the children born in the US – the result of decades of heady immigration growth.

However, a recent slowdown in the growth of the Hispanic and Asian populations is prompting a rethink on when non-Hispanic whites are likely to become a minority.

New 2011 census estimates highlight changes in the nation's racial make-up and the prolonged impact of a weak economy, which is now resulting in fewer Hispanics entering the country.

Overall, the minority population rose by 1.9 per cent to 114.1 million, or 36.6 per cent of the total. This was partly the result of earlier waves of immigration that brought in young families and boosted the number of Hispanic women in their prime childbearing years – as reflected in the 2010 count, which showed more Hispanics than expected.