A jury started deliberations yesterday in the trial of a doctor accused of strangling a minutes-old baby he had tried to abort from its 18-year-old mother.

The judge told the panel that it could find Dr. William B. Waddill guilty of first- or second-degree murder, first- or second-degree attempted murder, or declare him innocent.

A possible manslaughter conviction was dropped from the judge's instructions at the request of the attorney for Waddill, an obstetrician and gynecologist who has one of the largest practices in Orange County.

The complex case involves two radically conflicting stories on the events that followed a saline abortion attempt at Westminister Community Hospital on March 2, 1977.

Waddill had injected the salt solution into the womb of Mary Weaver to induce a routine abortion and left after the procedure was completed.

Twelve hours late, members of the hospital staff Waddill to say that the abortion had failed and Weaver had given birth to a live baby, which was crying, breathing and had a heartbeat.

Nurses testified they were giving resuscitation to the baby when Waddill returned to the hospital and ordered them to stop it and leave the nursery.

Waddill testified that he found the infant "pale and cold and lifeless" and put his hands on the baby to try to locate a pulse, but found her dead. He testified that the fetus had been killed by the saline solution and that what nurses took for signs of life were merely twitches of a dead fetus.

But Dr. Ronald Cornelsen, a pediatrician who remained in the hospital nursery with Waddill, testified the baby was indeed alive and he saw Waddill choke the infant four times.

He said Waddill told him the baby must be killed because she would be severely brain-damaged by the saline solution and he would be hit by a multimillion-dollar malpractice suit.