The employment cost index rose 0.3% in the first quarter, after increasing 0.5% during the fourth quarter, according to a report by the Labor Department's Bureau of Labor Statistics released Tuesday.
Economists polled by Thomson Reuters predicted a 0.5% increase.
The index measures the cost of wages and salaries, which makeup about 70% of employment costs, as well as benefits, which make up the remaining 30%. Wages and salaries increased 0.3%, and benefit costs rose 0.6%.
The Bureau of Labor Statistics said that when the gain or loss of the employment cost index is lower than those of its components, the rounding of numbers is the primary cause because it calculates the published percent changes based on the published rounded index numbers.
For the 12-month period ending in March, the index rose 1.8%