U.S. worker productivity decreased for a second straight quarter, and employer costs for labor climbed by the most in more than a year.

Worker productivity slumped in the fourth quarter by the most in almost two years, leading to a pickup in U.S. labor costs that threaten corporate profits.

Worker productivity unexpectedly grew in the third quarter, reflecting a slump in the number of hours worked by self-employed Americans.

Worker productivity struggled to gain traction in the second quarter after slumping over the previous six months, leaving intact the diminished efficiency that’s defined the current U.S. economic expansion.

The productivity of U.S. workers rose more than projected in the third quarter, helping to contain labor costs even as employment picks up.

U.S. workers’ productivity rose in the second quarter at a slower rate than previously estimated, the Labor Department reported.

The productivity of U.S. workers rose more than projected in the second quarter, rebounding from the biggest drop in more than three decades and helping to restrain labor costs.

The measure of employee output per hour dropped at a 1.7% annualized rate, the weakest reading in a year, after rising at a 2.3 % pace in the last three months of 2013, the Labor Department reported.

U.S. workers’ productivity rose in the fourth quarter at a slower rate than previously estimated, the Labor Department reported.