Consumer prices rose 4 percent during 1984, the Labor Department reported yesterday, enabling the Reagan administration to boast, "We have frozen inflation in place for three straight years."

And given recent trends in wages and other factors that influence prices, most economic forecasters expect at most a modest rise in inflation this year. Some expect no acceleration at all.

In December, the consumer price index rose a seasonally adjusted 0.2 percent, the same as the month before, the department said. For the three months ended in December, the CPI rose at only a 3.1 percent annual rate.

At the White House, spokesman Larry Speakes said the figures show that inflation "remains low and under control."

However, Commerce Department chief economist Robert Ortner noted that while a 4 percent inflation rate was low compared with the late 1970s, it is still high compared with other parts of the post-World War II era. "I'd love to see it down to 2 percent before the dollar falls," Ortner declared.

The CPI rose 3.8 percent in 1983 and 3.9 percent and in 1982.

The 4 percent change in consumer prices from December 1983 to last month was somewhat smaller than many forecasters had expected. Predictions of a 5 percent or greater rise were common a year ago, and a small group of economists focusing on past changes in growth of the money supply said that by now prices would be going up at a 7 percent to 9 percent rate.

Now the forecasts are more sanguine. "We don't really see any significant price increases in any of the categories," said Donald Ratajczak, head of the economic forecasting unit at Georgia State University.

"The world trend in inflation is downward, and our trend is even stronger because of the dollar," Ratajczak said.

However, some analysts warned that the current deep freeze that has hit the South could so damage fruit and vegetable crops that the CPI could rise sharply for a month or two.

In general, a faster rise of prices of services of all types last year was largely offset by a lower inflation rate for commodities, including food. Services prices were up 5.4 percent during 1984, compared with 4.8 percent in 1983 and 4.3 percent in 1982.

As it does each year, the cost of medical care rose substantially. It was up 6.1 percent in 1984, a slightly smaller rise than the 6.4 percent recorded the year before. Personal and educational expenses jumped 9.1 percent, but that, too, was less than the 9.9 percent of 1983.

Commodity prices, strongly influenced by continuing declines in oil prices and plentiful supplies of food items, went up 2.6 percent, less than the 2.9 percent increase in 1983 and 1982's 3.6 percent.

Some analysts fear that the slow but steady acceleration of inflation in services, which account for slightly less than half the total CPI, is laying the groundwork for an eventual acceleration of the whole index.

For instance, a decline in the value of the dollar on foreign exchange markets -- to which Commerce's Ortner alluded -- would tend to increase the cost of imported commodities, whereas the dollar's rise in value over the last three years has helped hold down prices of both imported and domestic commodities.

There is substantial disagreement among analysts over just how much a drop in the dollar's value would add to inflation. One estimate, from Wharton Econometric Forecasting Associates, is that a 10 percent decline in the dollar would add about 0.6 percentage points to the inflation rate in the first year and roughly that amount in the year following, assuming no further decline in the dollar. Many other estimates of the impact of a dollar decline are higher.

On the other hand, most forecasters also expect further drops in oil prices. Gasoline prices fell 2.5 percent in the 12 months ended in December and could fall again this year.

Altogether, the energy component of the CPI rose a minuscule 0.2 percent during the year. Had energy prices risen as much as the remainder of the index, the overall increase for 1984 would have been 4.5 percent rather than 4 percent.

Another major reason for last year's good price performance -- and the expectation that 1985 will be good, too -- is the relatively slow rate of increase in employe wages and fringe benefits.

Between the fourth quarter of 1983 and the fourth quarter of 1984, hourly compensation at private nonfarm businesses rose an estimated 4.3 percent. That is not much higher than in the four quarters of 1983 and well below the 7.2 percent rise during 1982.

"We are still above what anyone would call full employment, and that is having a depressing effect on wages," said economist Robert Westcott of Wharton Econometric Forecasting Associates. With the civilian unemployment rate not expected to fall during 1985 more than about half a percentage point from its December level of 7.2 percent, Wharton foresees little, if any, speedup in compensation gains.

However, if productivity growth slows from the estimated gain of just under 3 percent for 1984, there could be more pressure on prices from labor costs. To the extent that productivity -- output per hour worked -- goes up, the labor cost associated with producing that output is reduced.

In December, the CPI rose to a level of 315.5 before seasonal adjustment. That means that the market basket of goods and services composing the index that cost $100 in 1967, the base year, cost $315.50 last month.

For the month, food and beverage and medical care prices rose 0.3 percent and entertainment 0.5 percent -- all more than the 0.2 percent increase in the overall index.