Today in History—October 15: Putting the Power of Birth Control in a Pill

On October 15, 1951, Luis E. Miramontes, a chemist working in Mexico City at the pharmaceutical company Syntex, took a monumental step forward in a chemical synthesis process that would ultimately change birth control—and the world.

Miramontes was working to make a synthetic form of progesterone, a hormone that can be used to treat gynecological conditions such as irregular periods and endometriosis. With the assistance of chemists and mentors Carl Djerassi and George Rosenkranz, he successfully generated norethindrone (norethisterone), a synthetic progestin hormone that could be taken orally.

The discovery solved a deceptively difficult chemical problem.

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Progesterone was already known to play a role in regulating the reproductive cycle and suppressing ovulation. This made it especially interesting as a potential contraceptive. However, progesterone is quickly metabolized when taken by mouth, therefore requiring large doses to be effective and rendering it impractical as an oral birth control medication.

Norethindrone offered a solution. It acted as a progestin—a synthetic substance with effects that mimic those of progesterone—while also being effective at low doses.

This double-edged character was made possible by Miramontes’s brilliant thinking: He added a carbon-carbon triple bond to the chemical’s steroid structure and adapted the chemical recipe to suit Mexico City’s high altitude, using toluene instead of benzene as a solvent.

Norethindrone was a remarkable development in the quest for easy-to-use forms of birth control, opening the way for the advancement of oral contraception. Just two years later, the synthetic progestin norethynodrel, an isomer of norethindrone, was developed. Norethynodrel was selected for use in Enovid, which in 1960 became the first oral contraceptive approved by the U.S. Food and Drug Administration.

The pill’s consequences were immensely far-reaching. With reliable oral contraception, women had unprecedented control over their decision to become pregnant. This ability influenced all aspects of women’s lives—from reproductive health to family planning to educational and economic opportunities.

Oral contraception also fueled long-standing debates over reproductive rights and sexual freedom.

And it all came down to a chemist figuring out how to effectively capture a reproductive hormone in a pill.