Dr. Bernard N. Nathanson, an early abortion rights champion who oversaw tens of thousands of the procedures before having a change of heart and becoming a prominent anti-abortion activist, has died at age 84.

Nathanson died Monday at his Manhattan home after a long fight with cancer, said his wife, Christine Reisner-Nathanson.

Nathanson was an obstetrician-gynecologist who in 1969 helped found the National Association for the Repeal of Abortion Laws, now called NARAL Pro-Choice America. When abortion was legalized in New York the following year, he became director of the Center for Reproductive and Sexual Health, an abortion clinic.

He estimated that he oversaw about 75,000 abortions in the 1960s and '70s before turning away from abortion rights, his wife said.

It was while working at the abortion clinic that Nathanson said he developed misgivings about the procedure. He said the use of ultrasound images led to his change of heart.

After joining the anti-abortion movement, Nathanson lectured internationally. He was a frequent visitor to the Ronald Reagan White House and narrated the 1986 anti-abortion film "The Silent Scream," which graphically depicts the abortion of a 12-week-old fetus.

Nathan also produced "Eclipse of Reason," a film about a procedure opponents call partial-birth abortion, in which the fetus is partially extracted before being destroyed. He published several books, including an autobiographical account of his experiences.

His wife described him as a "real Renaissance man" and said he "had a lot of guts."

"When he was an abortion doctor he was seen as a pariah by the medical community, and when he went pro-life he was scorned by the women in the pro-abortion movement," she said.

Nathanson, born in New York to a Jewish family, converted to Catholicism in the late 1990s. He was baptized into the Catholic faith by the late Cardinal John J. O'Connor in a private ceremony.

He earned his bachelor's degree from Cornell University and a medical degree from McGill University in 1949.

He wrote in his memoir that he knew "every facet of abortion."

"I helped nurture the creature in its infancy by feeding it great draughts of blood and money," he wrote. "I guided it through its adolescence as it grew fecklessly out of control."

Besides his wife, Nathanson also is survived by a son, Joseph Nathanson.