The first oral contraceptive in history

Few medical innovations had a more massive and social impact than the contraceptive pill.

Only five years after its launch in the United States in 1960, some 6.5 million Americans used it.

Today, more than 100 million women around the world choose this form of protection against pregnancy, according to data from Harvard University.

“The pill” – as it is commonly known – is considered a milestone in feminism since it allowed women to have sexual relations without worrying about reproductive consequences.

And some also associate their creation with the emergence of the so-called “sexual revolution” of the 60s.

But the lesser known side of this pill has to do with the role played by Latin America in its development.

On the one hand because it was in a country in the region – Mexico – where a synthetic hormone that could block ovulation was created for the first time.

But the main role played by Latin America – or rather Latin American women – in the history of the pill is darker.

It has to do with the large-scale trials that were conducted in Puerto Rico to determine the effectiveness and safety of this revolutionary treatment, and that continue to be a source of shame for the scientific community.


The story goes back to 1955 . Scientists John Rock and Gregory Pincus , both linked to Harvard University, had successfully developed a pill that prevented ovulation.

They used synthetic hormones, an advance that had been achieved in part thanks to the work of Mexican scientist Luis Miramontes, who first managed to create a synthetic progesterone in 1951, in Mexico City, along with two colleagues.

Rock and Pincus needed to test the human pill to see its effects but were unsuccessful in recruiting volunteers in Boston, where they were based.

According to the Harvard Crimson newspaper, which last September wrote a story about the “dark history” of oral contraceptives called “The bitter pill” – many women gave up clinical trials due to the severe side effects .

These included “pain, blood clots , haemorrhages and nausea.”

Eager to move forward, doctors resorted to unethical practices : they tested their pill on mentally ill women who were patients at a Harvard-associated hospital.

But that did not reach either. If they wanted to get permission from the powerful US Food and Drug Administration. (better known as FDA, for its acronym in English), they had to perform massive trials.

Pioneers or guinea pigs?

It was then that the doctors decided to go to Puerto Rico .

Unlike the USA where there was legislation that restricted the use of contraceptives, in the Caribbean country they were allowed and even encouraged by the authorities, who wanted to stop population growth.

The scientists settled in Rio Piedras, a humble neighbourhood in the municipality of San Juan, and recruited low-income women.

It is estimated that over several years close to 1 . 500 women participated in the tests.

“The study did not include financial compensation but they never had problems getting volunteers,” reports the Crimson.

Why? This was explained in 2004 to The Orlando Sentinel newspaper Delia Mestre, one of the Puerto Ricans who participated in the trials:

“We quickly joined in. The women were told that it was a medication that would prevent them from having children they could not keep,” she said.

At that time many women used sterilisation or abortion to avoid having more children.

However, what was particularly controversial is that scientists do not you s informed patients about the risks and side effects of the drug.

At that time, “the American researchers were not under obligation to obtain informed consent,” explains Crimson.

Therefore, doctors were not acting illegally although many believe that they behaved immorally .

The unethical clinical tests conducted in Puerto Rico led to the creation of new FDA rules that require participants to be better informed about the drugs they are testing.


Clinical trials proved successful. After a year in San Juan, the studies were extended to the municipality of Humacao, in the east of the country, and to the nearby Port-au-Prince, in Haiti.

However, according to the documentation left by Pincus and Rock, 22% of the participants abandoned the tests, due to severe side effects.

These were associated with the fact that the pills contained three times the amount of hormones they carry today.

According to the Washington Post, ” three women died during clinical trials, but no autopsies were performed, so it is not known if their deaths were linked to the drug.”

The creators of the pill even minimised its negative effects. In an interview with the New York Times, Pincus said that “these side effects are mostly psychogenic, mostly because women expect them to happen.

But in addition to ignoring their problems, the “parents of the pill” also abandoned their Latin American patients.

After concluding the clinical trials and once the FDA approved the oral contraceptive – whose trade name was Enovid – in 1960, the doctors left the Caribbean islands and never rewarded their patients or offered them the medicine they had helped create.

With a price of US $0.50 per pill, most of these women did not have access to the pill again.

Meanwhile, Pincus and Rock went down in history as two of the men who contributed most to women’s liberation.


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