Most major banks lowered their prime lending rates yesterday, but only by a quarter point to 12 1/2 percent rather than to 12 1/4 percent as Bankers Trust Co. of New York had done the day before.

Analysts said the smaller reduction at the other banks was due to a desire to keep profits up and to uncertainties over the course of interest rates over the next several weeks.

Most short-term rates have fallen by close to a percentage point since Sept. 1, and forecasters are divided over whether they will turn upward again before the end of the year.

Even small reductions in the prime rate are welcome to commercial and industrial borrowers whose bank loans carry floating rates. About half of all such loans now are tied to the prime, or a "reference rate," as it is called at some banks.

The banks' move on the prime is a lagging reaction to a sharp drop in their cost of money since early September. In addition to a lower cost of overnight money, rates on large certificates of deposits they sell to obtain lendable funds also have dropped significantly.

Part of the drop in short-term market rates, such as on CDs, is the result of an easing of worries over the problems at Continental Illinois National Bank and Trust Co, which was rescued from bankruptcy by federal regulators, analysts said.

At the same time, the Federal Reserve has eased its monetary policy stance somewhat as economic growth has slowed.

But probably the most important factor in the banks' decision to drop their base rate on which loans are priced is a continued slackness in business loan demand. Many large corporate borrowers have been turning to the commercial paper market, where rates have been lower.

Total credit demand has continued to grow, and the level of rates generally remains high relative to current inflation. But the slower pace of economic growth has eased pressure on interest rates.

Salomon Brothers economist Henry Kaufman, who earlier in the year predicted that rates would rise sharply before the end of 1984, said yesterday that he now expects only moderate increases through the first half of 1985 -- assuming that the value of the U.S. dollar does not decline sharply on foreign exchange markets.

Kaufman still expects the combination of large borrowings by the federal government to finance its budget deficits and continued strong private-sector demand for credit to produce much higher rates eventually. But that development has been pushed into the future.

"We should not underestimate the risk of large increases in interest rates in the final stages of this business cycle, but this is not a matter of immediate concern to federal policy makers or the market," Kaufman wrote in his firm's quarterly report on investment strategy.