U.S. consumer prices slid 0.1% in December, dropping for the first time in nine months as gasoline prices fell, the Labor Department said.

The consumer price index for all items was up 1.9% over the past 12 months, according to a press release from the Bureau of Labor Statistics on Friday.

"The seasonally adjusted decline in the all items index was caused by a sharp decrease in the gasoline index, which fell 7.5% in December," according to the press release. 

The moderate inflation rate could ease pressure on the Federal Reserve to maintain its three-year-long campaign to boost interest rates. Typically, the central bank raises borrowing costs to cool economic growth and keep inflation from spiking during times of expansion; as businesses hire more workers, wages typically rise, and those added costs are often passed on to consumers.

The drop in gas prices came just in time for the end-of-year holidays in the U.S., a time when more motorists take to the roads to shop, visit relatives and take vacations.   

Excluding volatile food and energy items, prices rose 2.2% over the past 12 months, matching the average forecast of economists in a FactSet survey. 

Last year's stock-market decline, coupled with signals from the bond market, have heightened speculation among investors that the economy is slowing, and possibly headed toward a recession as soon as this year.  

President Donald Trump has blamed the Fed for raising rates too quickly, unnecessarily hampering economic growth. 

The central bank, led by Chairman Jerome Powell, voted in December to raise interest rates to a range between 2.25% and 2.5%.

But more recently, Powell has expressed a preference for a "data dependent" approach on interest rates -- a signal that the Fed might pause its rate-hiking cycle if there are no imminent signs of runaway inflation.