The US economy grew at an annual rate of 3.8 per cent in the second quarter, less than previous estimates, the government said Thursday, according to dpa. Growth was revised downward for the April-June period from 4.0 per cent in an estimate released in August and followed an 0.6- per-cent expansion in US gross domestic product in the first quarter, the Commerce Department said. Thursday's estimate was revised downward to reflect an increase in imports and less spending on nonresidential buildings. US exports rose 7.5 per cent during the second quarter and imports fell 2.7 per cent, a trend that boosts GDP, the Commerce Department said. The numbers were the government's final GDP estimate for the quarter.