Bernard Nathanson, who performed or oversaw more than 60,000 abortions, only to undergo a change of conscience and become one of the most compelling national voices against the procedure, died Feb. 21 of cancer at his home in New York. He was 84.

An obstetrician-gynecologist, Dr. Nathanson helped found the National Association for the Repeal of Abortion Laws and once led the country's busiest abortion clinic.

He trained thousands of doctors to perform abortions and estimated that he personally ended 5,000 pregnancies. One of his patients in the 1960s, he later wrote, was his pregnant girlfriend.

But new technology, including ultrasound imagery and recordings of fetal brain and heart function, caused him to quit providing abortion services.

"For the first time, we could really see the human fetus, measure it, watch it, and indeed bond with it and love it," he wrote in his 1996 autobiography, "The Hand of God." "I began to do that."

He catapulted himself into the center of the roiling abortion debate of the mid-1980s with a 28-minute film called "The Silent Scream."

The movie uses ultrasound photography to show the real-time abortion of a 12-week-old fetus - grainy images that, according to Dr. Nathanson's narration, show a violent and frightening process.

"Once again, we see the child's mouth wide open in a silent scream," he says as the doctor inserts a suction tube. "For the first time, we are going to watch a child being torn apart, dismembered, disarticulated, crushed and destroyed by the unfeeling steel instruments of the abortionist."

The film - bolstered by the back story of Dr. Nathanson's high-profile about-face - became a sensation, widely distributed by antiabortion groups and screened at the White House by President Ronald Reagan, who urged members of Congress to see the movie and "move quickly to end the tragedy of abortion."

Abortion rights advocates criticized the film as inaccurate and emotionally manipulative but recognized its influence. In 1985, then-Planned Parenthood of America chairman Allan Rosenfield called the film "the most powerful thing the right-to-life movement has put out."

Dr. Nathanson produced a second film, "Eclipse of Reason," that explicitly portrayed late-term abortions.

In addition to his memoir, he wrote two other books, "Aborting America" (1979), with Richard Ostling, and "Abortion Papers: Inside the Abortion Mentality" (1983).

Bernard N. Nathanson was born to Jewish parents July 31, 1926, in New York. He graduated from McGill University medical school in Montreal and later served as a doctor with the U.S. Air Force.

His "introductory excursion into the satanic world of abortion," he later wrote, came in the 1940s, when he gave his pregnant girlfriend money for an illegal procedure. Two decades later, he performed an abortion on a different girlfriend.

"I swear to you that I had no feelings aside from the sense of accomplishment, the pride of expertise," he wrote.

He completed his residency at Woman's Hospital in New York, where his father had a long career as a teaching doctor. Dr. Nathanson later joined his father's private practice.

The Nathansons' father-son relationship soured when Dr. Nathanson married a non-Jewish woman, and the two parted ways professionally.

During the 1960s, before on-demand abortion became legal in New York, Dr. Nathanson provided abortions under regulatory loopholes that allowed for the procedure in the case of a woman's psychiatric or therapeutic need.

Having dealt firsthand with ill and injured victims of back-alley abortions, in 1969 he helped found the organization now known as NARAL Pro-Choice America. In the early 1970s, he led Manhattan's Center for Reproductive and Sexual Health, at the time the country's largest provider of abortions.

He left the clinic in 1972 and publicly announced his change of heart about abortion two years later, when he published an essay in the New England Journal of Medicine. But as obstetrical chief at New York's St. Luke's Hospital from 1972 to 1978, he continued to oversee and perform abortions he deemed medically necessary.

His antiabortion beliefs gradually hardened. By the late 1970s, he refused to perform the procedures and became an outspoken supporter of antiabortion laws.

In 1996, Dr. Nathanson - who had long described himself as a "Jewish atheist" - converted to Catholicism. He also received a degree in bioethics from Vanderbilt University.

His first three marriages ended in divorce. Survivors include his fourth wife, Christine Reisner-Nathanson of Manhattan; and a son from his third marriage, Joseph.

In his writings and speeches about abortion, Dr. Nathanson often referred to the guilt he felt about the work he had done before his convictions changed.

"I know every facet of abortion," he wrote. "I am one of those who helped usher in this barbaric age."