The percentage of new voters in the Maryland suburbs registering as Republicans has increased steadily in recent months, with the most dramatic surge to the GOP coming from high school students in Montgomery County.

In a trend that several voting analysts said may be paralleled nationwide, nearly 40 percent of the 18-year-olds who registered in Montgomery last month signed up as Republicans, a jump of about 10 percent from 1979 and the preivous eight years.

"This is striking, it's a real punch in the gut to the Democrats," said Marie Garber, a veteran Democratic elections board supervisor in the suburban county, where the traditional proportion of registered Republicans has rested at about 30 percent.

The new registration figures, which Garber said "serve as a pretty good barometer of public sentiment," show that in both Montgomery and Prince George's counties the shift to the Republicans has not been limited to 18-year-olds.

In Montgomery, the percentage of new voters registering Republican has risen from 24 percent last month. The Republican increase in Prince George's has gone from 19 percent in December to 24 percent in February.

National and state voting analysts and party officials offer varying reasons for the Republican surge among new voters.

"I think this started because of middle-class enthusiasm for George Bush and is fed now by the enthusiasm for John Anderson," said Richard Scammon, director of the Election Research Center in Washington, "I'd say it's more the appeal of a particular candidate than for the party or disenchantment with the Democrats."

Dr. Alan Levey, the Republican State Committee chairman in Maryland, disagreed somewhat, arguing that the GOP registration boost was caused mainly "by the fact that people are unhappy with the Democrats and the Carter administration. They can't blame the Republicans for what's gone wrong because we haven't been responsible for it."

Levey, whose state party has reluctant pushed voter registration drives in the past because "we knew we'd be signing up three Democrats for every Republican," said that policy has been changed in light of the new registration figures. He said the party has launched registration drives in all 23 counties and Baltimore, with prizes going to the precinct and county bringing in the highest percentage of Republican voters.

In support of the theory that specific candidates were responsible for the shift to the Republican, election board officials throughout Maryland said they were besieged with calls from Democrats who wanted to switch party affiliations the day after the primaries in Massachusetts and Vermont, which catapulted liberal John Anderson into contention.

"That was the busiest day I can remember except for a day before an election," said an elections board official in Anne Arundel County.

The deadline for switching party affiliations for Maryland's May 13 primary was Jan. 15, however, so the callers were frustrated in their efforts to be registered as Republicans.

The registration of 18-year-olds in the high schools of Montgomery County was a bipartisan effort conducted by the county's board of elections. In the last five days of February, registrars set up tables in all public high schools and seven private schools in the county, registering 3,712 new voters.

Of that number, 49 percent registered as Democrats, 39 percent as Republicans and 12 percent as independents. Since the high school registration program started in 1971, the Democratic proportion had never before fallen below the 55 percent mark and the Republicans had never before garnered more than 27 percent of the 18-year-olds.