Chief Justice Warren E. Burger yesterday lifted the final legal obstacle preventing a Maryland woman from obtaining an abortion for her severely retarded daughter, who was raped nearly six months ago while under the care of two institutions for the handicapped.

Burger, who blocked the abortion Thursday afternoon, gave no reason for declining to review the case.

Burger's decision, which involves a pregnant 19-year-old woman from Silver Spring, came amid nationwide publicity over her plight and coincided with offers from right-to-life groups to arrange an adoption for the child if the pregnant woman's mother decides against an abortion.

A Hagerstown lawyer, who has argued against abortion in several well-known cases, disclosed yesterday that he helped initiate the legally complex chain of events that ended with Burger's decision.

"To take the life of this unborn child is murder," said R. Martin Palmer Jr., who argued against the abortion at an Oct. 4 hearing in Montgomery County Circuit Court. Accompanying Palmer at the hearing was Gerard E. Mitchell, who, in an unusual move by Judge William M. Cave, was appointed attorney for the fetus, now about 24 weeks old.

Mitchell, a member of a Maryland right-to-life group, attempted to stop the abortion but was rebuffed by the Montgomery circuit court and later by two state courts in Maryland. This week he appealed to Burger to reverse the lower court decisions.

Mitchell, strolling his 17-month-old son outside his home in Bethesda yesterday, said he was abandoning his effort to stop the abortion.

"I had hoped this child would see the light," he said. "If judges could see abortions, they wouldn't be doing things like this."

Some civil rights groups initially criticized Burger for temporarily blocking the abortion. Suzanne Lynn, a lawyer with the American Civil Liberties Union in New York, said it would have been illegal for Burger to permanently block the abortion.

"The fetus is not a person and does not have rights that are recognizable under the law," said Lynn.

Lynn also sharply criticized Cave's decision to appoint Mitchell to represent the fetus, which she said is not entitled to counsel under the law.

In the same hearing where Cave designated Mitchell attorney, the judge also allowed the mother of the woman to seek an abortion for her daughter, but not without some deliberation. At one point, Cave asked the woman's physician what would be her advice to the woman, were the patient lucid. The physician replied that she would recommend the woman give birth to the child.

Roy Niedermayer, attorney for the mother of the pregnant woman, said Burger's decision yesterday "legally empowers" the pregnant woman's mother to arrange an abortion.

However, it is now unclear whether the woman's mother will do so. In recent court hearings, medical experts have testified that an abortion at this stage poses risks to the mother, dangers that increase as the abortion is delayed.

The mother of the pregnant woman was informed of Burger's decision shortly after it was announced and was consulting with family members and physicians.

The pregnant woman, meanwhile, was reported to be staying at the Great Oaks Center in Silver Spring, one of two facilities for the handicapped where she was under care at the time she was raped. Maryland State Police, who are investigating the sexual assault, have made no arrests in the case.

"We're trying to find the child's grandmother to appeal to her to not let the abortion go through," said Michael P. Farris, a staff lawyer of a group called Concerned Women for America, a pro-life organization with offices in Washington and San Diego.

A private agency in Maryland already has guaranteed the child's adoption and Concerned Women would pay any related expenses, said Farris, adding that the organization unsuccessfully sought the intervention of the White House and the U.S. solicitor general.

The pregnant woman is deaf, mute and blind because her mother contracted rubella, or German measles while she was pregnant with her. Her handicaps are not transferable to the fetus, according to medical testimony in the case. Farris said his organization "will guarantee adoption regardless of handicap, race or anything."

Several Catholic organizations also were reported to be trying to locate the pregnant woman's mother. And Guy Lunsford, 33, an Air Force captain and father of four, said he informed Burger's office that he was willing to adopt the child.

"If they would let the baby go to term, I am willing to take responsibility for it," said Lunsford, a Catholic.