The US economy expanded less than initially estimated in the first quarter, government data showed Thursday, while a key inflation gauge separately hit a three-year high on fallout from the Middle East war. The figures sound a warning on pressures that American households are facing ahead of midterm elections, as steeper gasoline prices squeeze budgets and a boost from tax refunds fades. Gross domestic product in the world's biggest economy rose at an annual rate of 1.6 percent in the first three months this year, the Commerce Department said. This was down from an earlier estimate of 2.0 percent, with the pullback "primarily reflecting downward revisions to investment and consumer spending," the department added.