WASHINGTON — The U.S. economy’s slowdown in growth at the beginning of the year wasn’t quite as bad as first thought, thanks to a bigger boost from housing and less drag from business investment and trade.

The gross domestic product, the broadest measure of economic output, grew at an annual rate of 0.8 percent in the first quarter, slightly better than the 0.5 percent first estimated, the Commerce Department said today. But the revised rate is still the weakest pace in a year.

It was the second lackluster quarter in a row, following a modest 1.4 percent gain in the fourth quarter. At the beginning of this year, the economy was held back by turbulence in financial markets and global economic problems.

Economists are forecasting a rebound in the current quarter to growth of around 2 percent. They expect continued solid gains in employment, which in turn should support increased consumer spending.

For the first quarter, consumer spending, which accounts for 70 percent of economic activity, grew at a 1.9 percent rate. That was the weakest performance in a year, reflecting a sharp slowdown in auto sales.

The upward revision from the initial estimate of 0.5 percent reflects a weaker drag from business investment in structure and equipment, primarily because of new-found strength in construction of commercial structures such as shopping centers. In addition, the trade deficit did not widen as much as previously estimated and businesses did not slow their restocking of store shelves as much as first thought.