ANNAPOLIS, SEPT. 12 -- The decisive defeats of key antiabortion legislators in Maryland's Tuesday primary may give a boost to abortion-rights advocates around the state, but not necessarily elsewhere in the nation, political observers said yesterday.

In Maryland, the abortion-rights movement was better financed and organized than it is in many other states, and its strategy of targeting local races succeeded in shifting the makeup of the newest battleground on abortion: the state legislature.

Abortion opponents prevailed elsewhere, however, winning most of the important races in New Hampshire, Minnesota and Wisconsin on primary day.

The Maryland results promise significant change in the heavily Democratic, 47-member state Senate, where abortion-rights legislation was blocked earlier this year by an antiabortion filibuster.

So impressed was Gov. William Donald Schaefer by the primary results that today he said he plans to refine his vague position on the issue. In the past, Schaefer has said only that he opposes laws that outlaw abortion.

After watching the primary contests, Schaefer said he will announce his stance next week.

"It is not going to be any startling issue," Schaefer said. "I am just going to say where I stand."

Pollster William Hamilton, who recently completed a survey for Planned Parenthood, said today that Maryland offered a good example of how abortion can be a deciding factor in state legislative races.

"In legislative races you get a smaller group of the electorate, and that allows one side or the other to get that constituency," said Hamilton, whose recent national polls showed that voters support abortion rights by 58 to 40.

Hamilton said voters are most likely to be motivated by candidates who take drastic stands on abortion.

"The fact in Maryland was that they were high profile, and filibustering puts you on the extreme end of the issue. That makes a candidate vulnerable if the constituency is on the other side."

Nancy Myers, a spokeswoman for the National Right to Life Committee, conceded the setback in Maryland legislative races, but noted that Rep. Roy P. Dyson (D-Md.) won renomination easily in the 1st Congressional District over an abortion-rights challenger, state Del. Barbara O. Kreamer (D-Harford).

"Our general position on what Maryland means nationally is 'not much,' " Myers said.

On the other side, Kate Michaelman, president of the National Abortion Rights Action League, called Maryland one of the "bright spots" on the political map for her group in Tuesday's voting.

"It shows that, at least in certain races, when you can focus the voter and combine good voter education, media and grass-roots organizing, it can be effective," Michaelman said today.

"But we don't think that abortion is a silver bullet. We have a long way to go in many places to match the organization of the other side, which has been organizing for 17 years. We've actually come far in a year and a half."

Abortion-rights groups claimed victory in four of the five state Senate races, including three in the Washington suburbs, in which abortion was a major issue.

"Wherever we were able to make the right to choose an issue, it worked in our favor decisively," said Karyn Strickler, executive director of the Maryland affiliate of the National Abortion Rights Action League.

Voters in Montgomery County handed lopsided victories to two abortion-rights Democrats: Del. Patricia R. Sher, who defeated veteran Sen. Margaret C. Schweinhaut, and Del. Mary H. Boergers, who beat Sen. S. Frank Shore.

Both Schweinhaut and Shore opposed abortion, as did Sen. Frank J. Komenda, who was defeated in Prince George's County by Del. Gloria Gary Lawlah.

In Baltimore County, the leader of antiabortion senators, Francis X. Kelly, was beaten decisively by teacher union leader Janice Piccinini.

"I certainly think the freedom-of-choice issue was the big issue," Sher said today. "I was not surprised because I know where the American people are."

With one Baltimore race still too close to call today, abortion-rights advocates appeared certain to gain at least one seat in the Senate.

Four more general election contests also could hinge on the abortion issue.

Michael Burns, chairman of the Maryland Right to Life Political Action Committee, said the low turnout accentuated the power of special-interest groups in the primary.

"We lost fair and square, but that's not to say that because {a fraction} of the state's voters don't agree with me that the state has repudiated us," Burns added.

While the governor prepares his position, antiabortion senators who survived the tide predicted there would be no recurrence of the filibuster that hamstrung the General Assembly this year, clearing the way for passage of an abortion-rights bill that could then be petitioned to a statewide referendum in 1992.

"One thing you have to give us credit for is that we can count," said Sen. Thomas Patrick O'Reilly (D-Prince George's), an antiabortion legislator who faces a Republican opponent in November who favors abortion rights.

Staff writer Howard Schneider contributed to this report.