Celebrating Mexico’s Contributions to the Birth Control Pill

September 15 to October 15 is National Hispanic Heritage Month. We’re celebrating by shining the spotlight on Mexico’s role in developing the birth control pill, one of the most important medical breakthroughs of the 20th century.


Humanity cannot fully unlock its potential until we release the bonds of oppression from all marginalized groups.


Underneath the surface of a large swath of Southern Mexico’s jungles lay the enormous roots of a wild yam, Dioscorea composita, known locally as barbasco. Mostly it was considered a nuisance, as it could get in the way of subsistence agriculture, but it did have its uses in traditional medicine — and it would change history forever when scientists figured out how to wrest valuable chemical compounds from it, a discovery that led directly to the development of the birth control pill.

Russell Marker. Image: Penn State University ArchivesIn the 1940s, hormones held an untapped potential for research, but there was no cost-effective method of producing large quantities of them — including progesterone, the Pill’s essential ingredient. An American chemist named Russell Marker set out to find a way to synthesize progesterone in abundance, hypothesizing that plants from the genus Dioscorea, which includes yams and agaves, would be a good source for starting material. After some research, he set his sights on wild-growing yams that were found only in Mexico.

Marker’s hunch brought him south of the U.S. border, where locals helped him find and gather these yams, enabling him to develop a method for synthesizing large batches of progesterone — more than had ever been in one place. When pharmaceutical companies would not invest in further research in Mexico, Marker relocated to Mexico City and put his money where his mouth was. In January 1944, he co-founded a lab named Syntex — a portmanteau of “synthesis” and “Mexico” — devoted to finagling hormones from wild Mexican yams. That yam was called barbasco by the indigenous population, and it was the industry’s choice for the raw material in hormone synthesis.

Barbasco and the Roots of Modern Contraception

Barbasco didn’t just yield progesterone for birth control pills — it also could be synthesized into cortisone, another steroid hormone that revolutionized medicine. Mexico became a major player on the steroid-hormone scene in Europe and the Americas — and the government and industry pumped money into university-level chemistry and botany education to produce subsequent generations of Mexican scientists.

But the raw material for steroid hormones was provided by campesinos — Mexican peasants whose invisible labors were crucial to the synthesis of progesterone and the medical advances that followed.

Though they were paid subsistence-level wages, and the work itself was dangerous and backbreaking, campesinos were putting Mexico on the scientific map. Scientists depended on the campesinos’ knowledge of soil conditions, growth cycles, and weather patterns, as well as their ability to differentiate between different species of yams. The campesinos used their knowledge of root coloration, leaf characteristics, vine width, and size variation to determine when they could dig up roots with the highest concentrations of sapogenin, the chemical that was converted into progesterone. The biggest specimens could weigh in excess of 100 pounds — these aren’t your mother’s Thanksgiving yams!

The barbasco trade was exclusive to Mexico because the wild yam was never successfully transplanted in the United States, and even when it could be grown in other places, such as Guatemala and Puerto Rico, the concentration of the desired chemicals was significantly lower when compared with plants in their native range. Every week, during the barbasco trade’s peak, more than 10 tons of the plant were removed from tropical Mexico.

Putting Progesterone into a Pill

By 1950, progesterone could only be given intravenously, and was being used to prevent miscarriage and treat excessively heavy menstrual periods. But injections were not convenient — before synthetic progesterone could fulfill its contraceptive potential, it had to be formulated as a pill.

Luis Ernesto MiramontesLuis Ernesto Miramontes was a promising chemistry student in Mexico City when he began his tenure with Syntex. Recognized for his talents conducting meticulous experiments, he was tasked to find an oral replacement for progesterone injections. It would have to be highly potent — so it could be delivered in a tiny pill — and had to remain stable even after hitting the acidic stomach.

By 1951, Miramontes and his colleagues had come up with the new and improved synthetic progesterone. They tested it, first on nonhuman animals and then on human subjects who suffered from excessively heavy menstrual periods. The new compound, when administered orally, was eight times more potent than the progesterone synthesized by the body. They called this new chemical norethindrone.

Now that progesterone could be synthesized cheaply and could be taken orally, the pieces were in place for the development of the birth control pill. The Pill itself was developed in the United States, building on crucial discoveries made in Mexico, and dependent upon the country’s barbasco supply. Key players in the Pill’s development also included women, like Margaret Sanger and Katharine McCormick, and Jewish refugees and their children, like Carl Djerassi, Gregory Pincus, and George Rosenkranz — folks who bravely confronted deep-seated taboos surrounding sex, reproduction, and gender roles. This fruitful collaboration — across lines of gender, class, nationality, immigration status, and religion — serves as a powerful reminder to humanity that we cannot fully unlock our potential until we release the bonds of oppression from all marginalized groups.

In 1960, when the FDA approved the birth control pill, more than 100,000 campesinos were harvesting barbasco. By 1974, Mexico had provided the world with nearly a billion tons of the wild yam. By the end of the 1970s, however, barbasco was obsolete — usurped by soybean products as the starting material for progesterone and other steroids.

Barbasco still grows in Mexico’s jungles, and university-level science education in Mexico owes a debt to the boost it was given when the country enjoyed prominence as the world’s premier supplier of steroid hormones. And the world, for its part, owes an incredible debt to Mexico for the role it played in revolutionizing women’s ability to control their own bodies.

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