In 1912, a nurse named Margaret Sanger was dreaming about pills.  The Pill, to be exact.
 
“She had this thing in her mind, like a fantasy,” says Jonathan Eig, author of the book The Birth of the Pill: How Four Crusaders Reinvented Sex and Launched a Revolution. What if, Sanger mused, there was some miracle tablet that would let women turn on and off their reproductive systems?
 
The idea resonated with Katharine Dexter McCormick, a wealthy progressive suffragette, who agreed to finance the project. But finding a hormone expert willing to work on a “women’s issue” – especially one as controversial (and illegal, in many states) as birth control – was no easy task. "This was just such a neglected area of science," Eig says of the ambivalence of the scientific community.

Sanger’s luck changed in 1951 when she met Gregory Pincus, a physiologist with a serious case of underdog syndrome.

Pincus, who had been fired by Harvard, was running a small lab out of Worcester, Massachusetts. "When Sanger met him, he says, ‘Of course I can make a birth control pill. Why would that be difficult?'" says Eig. “Science was really exciting in the ‘50s.”
 
Pincus’s concept for the drug was simple: when a woman is pregnant, her body releases a hormone called progesterone to halt further ovulation. Pincus developed a pill made of progesterone, and tested it successfully on animals in the lab.
 
Then came the hard part – finding human subjects.
 
This is where the group had to get a little sneaky, says Eig. Together with OB-GYN John Rock, they identified women being treated for infertility. They gave them high doses of the Pill, calling it “a rest for their reproductive systems,” and tracked their ovulation. Pincus also tested the drug on women in the slums of Puerto Rico and in insane asylums.
 
By 1957, when they were ready to take the drug to the FDA, momentum for the Pill was already off the charts, and opponents had a hard time catching up. When the FDA approved it for menstrual regulation later that year, “women were lining up for it,” says Eig. “Doctors were prescribing it, knowing what it really did, and the horse was out of the barn.”
 
Women began using their new freedom to get college degrees, delay marriage and childbearing, and reimagine the balance of power between genders. “It reinvented what it means to be a woman,” says Eig, “what it means to be in a relationship, and what it means to be human on this planet, in many fundamental ways.”

“I don’t think we’d have women on the Supreme Court today without the Pill,” he adds.