The government's index of leading indicators-- designed to foreshadow changes in the economy--rose in April for the first time in a year, the Commerce Department reported yesterday.

Commerce Secretary Malcolm Baldrige said the 0.8 percent upturn in the index was "welcome" and "good news." But he cautioned, "It would be premature to draw any firm conclusions about the timing of a business upturn." Murray Weidenbaum, chairman of the president's Council of Economic Advisers, called the report "a welcome straw in the wind," but he said he did not "draw any heroic conclusions from it."

Treasury Secretary Donald T. Regan, however, took a more optimistic view of the report, saying "today, we saw hopeful signs in the leading economic indicators that the recession is ending and the recovery is beginning."

Several private analysts said that the April rise in the index, the first increase since April 1981, could easily be reversed in May, and that it did not reflect strength in the industrial sector of the economy.

The Commerce Department reported that five of the 10 indicators in the index turned up last month, while four declined and one was unchanged. Robert Ortner, the department's chief economist, said "half of the indicators were up and half down, and from my personal point of view the wrong ones were down."

The indicators that were down included new orders for plant and equipment--a leading indicator of how much business is likely to spend on new investment in the near term--and new orders for manufactured consumer goods. Both tend to rise just before the whole economy picks up.

In contrast to this, the financial indicators that did show strength in April "tend to have longer lead times prior to the bottoms of recessions," Baldrige said. Among these indicators were stock prices, changes in "real" money supply, after adjusting for inflation, and changes in liquid assets. The latter figure "is subject to considerable revision for a number of months," Baldrige said.

Economist Allen Sinai of Data Resources Inc., characterized three out of the five numbers that contributed to the upturn as "soft" numbers, which may easily be reversed in May. Stock prices rose in April, but fell this month. Building permits also climbed in April, but in the same month housing starts dropped sharply, putting a question mark over the likely recovery in the housing industry.

High interest rates are the main cloud hanging over the economic recovery, analysts say. "The fact that mortgage rates remain high is not encouraging for near-term housing activity," Baldrige said. And although the rise in liquid assets suggests that people and businesses have more money to spend, higher interest rates may encourage them to save it instead, Ortner said.

Most economists are expecting that the individual income tax cuts due in July will boost the economy, although they warn the upturn may be anemic if interest rates stay high.

Sinai said "the recession is not as bad as it was" but that he would interpret the April rise in the leading indicators with caution. "I don't think we'll have a recovery before" the tax cuts, he said. "We will have one after, but the question is when?"

Yesterday's report "suggests that the economy may have finally bottomed out, but it will probably continue to stagnate until July," according to the National Association of Manufacturer's chief economist Jerry J. Jasinowski.

The good news from the financial indicators that climbed in April is that they suggest that the Federal Reserve had eased monetary conditions, he said, adding that the Federal Reserve was "clearly doing the right thing."

Many economists believe that tight money policy has been holding interest rates up and slowing the economy's growth. However, some administraton officials have recently commented that the Federal Reserve has not held money growth very tight in the last six months, and have warned against any loosening.