A hormone that blocks ovulation
The scientific basis for an oral contraceptive rested on a specific hormonal claim: that progesterone, a hormone the body produces after ovulation, could be given artificially to suppress ovulation before it happened, preventing pregnancy by stopping an egg from being released at all. Gregory Pincus, a biologist who had co-founded the Worcester Foundation for Experimental Biology in Massachusetts, worked with Min Chueh Chang to confirm this effect, establishing progesterone’s ability to block ovulation as the working principle behind what would become the pill. Turning that principle into a usable medicine still required a form of the hormone that worked reliably when taken by mouth and a way to test it safely in people.
Funding from outside the lab
Pincus’s research reached the scale it needed largely because of funding secured from outside conventional scientific channels. Margaret Sanger, the birth control advocate, met Pincus in 1951 and arranged initial support through the Planned Parenthood Federation of America, then introduced him in 1952 to Katharine McCormick, a wealthy suffragist and biologist who, from 1953, increased her funding of the project roughly fiftyfold over what it had previously received. That money let Pincus expand from laboratory work into human trials, beginning with physician John Rock’s tests of progesterone and, later, several progestin compounds on infertility patients in the Boston area in 1953 and 1954.
From infertility patients to a mass trial
The trial then moved to a larger and more vulnerable population: from 1955, Pincus and Rock tested the compound, marketed as Enovid, on women attending birth control clinics in Puerto Rico, a location chosen partly because an established network of roughly 67 clinics already served low-income women there and local conditions around contraceptive testing were less restrictive than on the mainland United States. The Puerto Rico trials, along with subsequent testing in Haiti, Mexico and Los Angeles, provided the data on effectiveness and side effects that would eventually support a case for regulatory approval, gathered from a population with markedly less social and economic power than the Massachusetts patients Rock had studied first.
A warning that was overruled
Edris Rice-Wray, who supervised the Puerto Rico trial, reported that Enovid gave complete protection against pregnancy but caused side effects serious enough, in her judgment, to make it unacceptable for general use. Pincus and Rock disagreed, drawing on comparisons with placebo groups and their experience with patients in Massachusetts, and did not treat her assessment as a reason to halt or substantially redesign the trial. That disagreement, over how much discomfort and risk was an acceptable price for effective contraception, and over how much weight a field researcher’s direct concerns should carry against the judgment of the scientists running the wider programme, was not resolved before the drug moved toward approval.
Approval, and a rapid global reach
The Food and Drug Administration approved Enovid for contraceptive use in May 1960, making it the first oral contraceptive available in the United States. Used correctly, combined oral contraceptive pills of this kind fail to prevent pregnancy in roughly three cases per thousand each year, though typical, less than perfect use raises that failure rate closer to nine per hundred; both figures represented a substantial improvement in reliability over the contraceptive methods most widely available before it. Uptake was rapid and lasting: the pill is now used by well over 100 million women worldwide, remains on the World Health Organization’s list of essential medicines, and is widely credited as a catalyst for broader changes in sexual behaviour and women’s participation in education and work.
Why the trial history belongs in the story
This history is worth understanding as a single, unresolved whole rather than splitting the science from its costs: the same programme that gave millions of women reliable control over pregnancy also ran its largest trial on women with comparatively little power to refuse or fully weigh the risks, and overrode a direct warning about side effects from the researcher closest to the patients. None of that erases the pill’s real and lasting effect on women’s lives, documented in its continued use by over 100 million people and its place among the world’s essential medicines, but it does mean the achievement and the ethical discomfort belong in the same account rather than in separate ones.