By Karna Swanson 

NEW YORK, FEB. 21, 2011 (Zenit.org).- Dr. Bernard Nathanson, the obstetrician and leading pro-abortion advocate who changed his views on abortion and later converted to Catholicism, died today at the age of 84.

Once a leader of the pro-abortion movement, Nathanson was a keynote speaker at the First National Conference on Abortion Laws in 1969, and that same year he was a founding member of the National Association for the Repeal of Abortion Laws, which is now known as NARAL Pro-Choice America.

Nathanson estimated that he was responsible for some 75,000 abortions -- he personally performed some 5,000 procedures, including one of his own son on a pregnant girlfriend -- before changing his views on abortion in the 1970s.

He wrote in his autobiography that the development of ultrasound technology, which enabled him to see images of unborn babies, influenced his change of heart. He soon became an avid pro-life activist, famously stating that abortion is "the most atrocious holocaust in the history of the United States."

He made two influential documentaries on abortion: “The Silent Scream” (1984) and “Eclipse of Reason” (1987).  He wrote “Aborting America” in 1979, the year he performed his last abortion, and published his autobiography in 1996, titled “The Hand of God: A Journey From Dath to Life by the Abortion Doctor Who Changed His Mind.”

Nathanson described himself as a Jewish atheist, and he converted to Catholicism in 1996, with the aid of Opus Dei priest Father C. John McCloskey.  He was baptized that year by Cardinal John O’Connor in St. Patrick’s Cathedral in New York on the feast of the Immaculate Conception.

“Nathanson was a bellwether figure in the pro-life movement,” Father McCloskey told ZENIT. “His conscience  led him, a brilliant atheist Jew and medical doctor, to acknowledge the evidence that scientifically shows that the the unborn child is such from conception, and its life must be protected from conception until a natural death.”

“In parallel fashion,” he added, “after many years of investigation he received the gift of the Catholic faith.”

Those present for the baptism included the now deceased Father Richard Neuhaus, Father Paul Marx and Msgr. William Smith. His godmother was the pro-life activist Joan Andrews-Bell.

“Nathanson dedicated the rest of his life to traveling tirelessly through the world to spread the pro-life message in writing and speech,” said Father McCloskey. “I believe his double conversion will be looked back to as a turning point in the struggle that will lead to a definitive end to abortion in the United States, and we hope, the world.”

Nathanson is survived by his wife, Christine, and a son.