Carl Djerassi, the chemist widely considered the father of the birth control pill, has died aged 91.

Djerrasi died of complications of cancer in his San Francisco home, Stanford University spokesman Dan Stober said. He was 91.

Born in Vienna and raised in Bulgaria, Djerassi  emigrated to the United States with his mother in 1939   . It was in a small accident in  1951 that he discovered a way to make synthetic progestogen — the female sex hormone known as ‘nature’s contraceptive’ while working on an arthritis drug.

Djerassi, a professor emeritus of chemistry at Stanford, was most famous for leading a research team in Mexico City that in 1951 developed norethindrone, a synthetic molecule that became a key component of the first birth control pill.

“The pill,” as it came to be known, radically transformed the lives of many women. Use of the pill spread rapidly, producing vast economic and social effects. It gave women control over fertility. It helped couples plan pregnancies and regulate family size, set women free to pursue educations and careers. It also generated debates over promiscuity and the morality of birth control. The Roman Catholic Church, in particular, emphasized its bans on artificial contraception.

Over the years, Dr. Djerassi lectured widely to promote the pill and faced controversies over possible side effects, including increased risks of blood clots, cancer and excessive bleeding during menstruation. He dismissed such claims, but estrogen and progestin doses in the pill were later reduced to cut the risk of side effects.

He mentioned in his book “This Man’s Pill,” that the invention changed his life, made him more interested in how science affects society.

In 1969, he submitted a public policy article about the global implications of US contraceptive research, according to the Stanford News Service. In 1970, he published another article about the feasibility of a birth control pill for men.

“The thoughts behind these two public policy articles had convinced me that politics, rather than science, would play the dominant role in shaping the future of human birth control,” he wrote.

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