Norwegians began voting today in a national election that is expected to topple Scandinavia's first woman prime minister in a political shift to the right caused by dramatic economic and social changes in this oil-rich welfare state.

Prime Minister Gro Harlem Brundtland, who took office eight months ago, and her left-of-center Labor Party, which has governed Norway in all but six years since 1945, are confronted by what is being called a "conservative wave" among voters, especially younger Norwegians, seeking new political leadership.

Many of the problems debated during the election campaign--high taxes, escalating social welfare and defense costs, persistent inflation and sluggish economic growth--are familiar in other Western industrialized countries, including the United States, where there have been significant political shifts.

But there is a difference in Norway. Once Europe's poorest country, it has become one of the richest after a post-World War II economic boom and a decade of oil production in the North Sea. The problem here, according to politicians, economists and social analysts, is coping with windfall wealth and rising expectations.

Norway produces six times as much oil and natural gas as it consumes. The rest is sold abroad, mostly to Western Europe and the United States, accounting for a third of Norway's foreign trade and 15 percent of its gross national product. This has pumped rapidly growing amounts of money into government coffers and private industry. Budget deficits have been wiped out and unemployment kept under 2 percent of the work force.

But at the same time, Conservative Party leader Kare Willoch, who is expected to be the next prime minister, said before the election campaign, "Things have been changing fast because of this enormous oil wealth and money falling down everywhere."

Especially high salaries in the oil industry conflict with Norway's long tradition of egalitarianism and the workers' solidarity of the union-based Labor Party. Wage inflation also has pushed many more Norwegians into the higher brackets of one of the world's most punishingly progressive income tax systems, depriving them of a larger share of the new oil wealth. Many young Norwegians who take the benefits of the generous welfare state for granted resent paying such high taxes to support it.

Brundtland said these and other effects of Norway's growing prosperity and the Conservative Party's political response to it have resulted in a "steady change from Labor to Conservative in the country," especially among younger voters. Unlike their parents' generation, Brundtland said, these younger voters "do not have a party allegiance by birth."

"Social and economic changes in recent years have been to the Conservative Party's advantage," said Henry Valen, Norway's leading academic analyst of political trends. "This is especially true of the increase in wealth and the rising level of education. The swing to the right has been noticeably strong among the younger generation, among those who have grown up since the Second World War."

"The Labor Party has been left with older union members who went through the Depression or the war and remember the long climb up," said Tim Greve, editor of the Verdens Gang newspaper in Oslo. "The young born into the affluent welfare state are leaving the party. Sons of union workers are now university professors and other well-paid professionals with ski chalets and beach houses. They don't march in May Day parades. They want six-hour days, five-week vacations, lower taxes and more take home pay."

According to opinion polls, these younger voters, called "modern Conservatives" by one senior Labor Party member, have moved to the somewhat right-of-center Conservative Party. It supports the welfare state but seeks to alleviate the tax burden, cut unnecessary public spending and curb government interference in business.

Party leader Willoch, 52, a dispassionate economist with an incisive debating style, describes his philosophy as resembling the supply-side economics of the Reagan administration, "but I don't agree with all that is said by supply-side economists."

Brundtland, 45, a physician whose warm, energetic personality has drawn large campaign crowds, has criticized Willoch's "Reagonomics" as a policy that has failed in Britain under Prime Minister Margaret Thatcher and gotten off to a shaky start in the United States. But to well-educated, affluent young voters, according to political analysts here, the Conservatives appear to be the party with new ideas.

"Labor is a victim of its own success," said one analyst. "There are no new social reforms to offer. And with taxes and inflation so high, it has had to start putting on the brakes."

Although Labor started curbing welfare-state spending and reducing the burden of marginal income tax rates, the Conservatives' biggest attraction is the promise to do more .

"There has been a growing reaction against the pretty extreme tax situation here," Willoch said. "There is an acceptance that you get something for your money, but the young are feeling it doesn't pay to work."

The Conservatives, long associated with business and urban voters, also appear to be gaining support from traditional centrist parties based in the agricultural valleys and fishing ports of mountainous rural Norway. Change also has invaded these areas, which not long ago were so isolated that a large number of regional dialects are still spoken along the long coastline. The election takes place over two days to allow time for votes from the most remote areas to be counted by late Tuesday, when the result should be known.

The old ports are becoming booming bases for the offshore oil industry. Employment has fallen in rural fishing, timber and agricultural industries despite subsidies from government oil revenues.

Ironically, subsidies the Labor government gave farmers have made many of them rich enough to abandon the traditional farmer-based Center Party for the Conservatives, according to analysts of public opinion polls. The Christian People's Party, which champions traditional values, also is having difficulty attracting younger voters.

"Innocent, rigid Norwegian society is going through a painful period of change," Greve said. He cited the psychological impact of suddenly being seen as such a rich nation thrust into world limelight and exposed to unprecedented international pressures because of its oil wealth and growing importance on the northern flank of NATO.

In one of the few security issues in the campaign, the Conservatives pledged to raise Norwegian defense spending to 4 percent above inflation each year from the 3 percent annual increase already being made by the Labor government, the biggest such increase in NATO outside the United States.

The Labor Party has been hurt, according to some of its leaders and opinion polls, by internal disagreement over Norway's relationship with NATO, including confusion over a proposal from Labor's left wing that Norway advocate negotiation of a treaty with the Soviet Union to keep Scandinavia free of NATO nuclear weapons if the Soviets reduce their nuclear arsenal near Norway. Norwegians appear surprised by the great concern this caused in other NATO capitals.

This was among a number of problems Brundtland inherited when she replaced the ill and indecisive Odvar Nordli as party leader and prime minister in February. She is credited with stronger leadership but appears to have failed to revive Labor's voter appeal sufficiently.