Before the Pill revolutionised women's lives, these female participants had to suffer.

When the contraceptive pill was approved by the American Food and Drug Association (FDA) on May 9, 1960, it became a watershed moment for feminism and gender equality.

Women now had greater control over childbearing and their careers, and could (mostly) protect themselves against unwanted pregnancies.

But while it’s all well and good talking about how revolutionary an invention the Pill was, we need to talk about the darker side of its creation.

Medical trials were needed to test how safe and effective it was, but what most people don’t realise is that there was mass exploitation of vulnerable women for these trials. Women who were mentally institutionalised in US asylums and impoverished Puerto Rican women participated in the early trials, sometimes unwittingly.

Mamamia’s daily news podcast The Quicky will get you up to speed on what you need to know today….

The Massachusetts pre-trials

Before the Pill was released to market, two of its creators, Harvard scientists Dr John Rock and Dr Gregory Pincus, had a problem.

It wasn’t money. Their project was encouraged and funded by prominent Women’s Rights activist and heiress, Katharine D. McCormick, but in order to get it approved by the FDA, they needed to prove the drug performed successfully in clinical trials.

After testing their formulation on rabbits, and an early version of the Pill on a 60-person study, Rock and Pincus realised they required bigger sample sizes. This is where the ethics get more than a little murky.

Due to their connection with Harvard University, some historians allege Pincus began conducting experiments on mentally ill patients at the Worcester State Hospital.

The Puerto Rico trials

Following their initial trials in the US, Rock and Pincus turned to the impoverished women living in the La Perla slums of San Juan, Puerto Rico.

The evident racism and classicism behind outsourcing this research was perpetuated by the idea of Eugenics - that the creation of a 'master human race' was possible by discouraging certain people from procreating - was still around in the 1950s, and the vulnerable women of the Puerto Rican slums proved to be the perfect candidates.

For one, the country had no laws against birth control and the overcrowding and high birth rate in the slums meant there was a demand for inexpensive means of contraception.

A year into the trial, nearly 25 per cent of the participants quit. Although the Pill was very effective at preventing pregnancy, it also was given at three times the dose than what is found today and participants frequently  complained of nausea, dizziness, depression and aches and pains.

Three women from the trial also died, but since no autopsies were conducted, it's unknown whether their deaths were the result of complications involving the drug.

Speaking to the Chicago Tribune, former participant and hospital social worker, Delia Mestre remained bitter over the lack of information given to the women involved in the trials.

"The experiments were both good and bad. Why didn't anyone let us make some decisions for ourselves?" she said.

"I have difficulty explaining that time to my own grown children. I have very mixed feelings about the entire thing."

According to a report from Planned Parenthood, Dr Edris Rice-Wray, the doctor in charge of conducting these trials, also had her concerns. She dubbed the original formulation unsafe, noting that 17 per cent of volunteers complained of nausea, headaches, vomiting and dizziness.

“It causes too many side reactions to be acceptable generally," she wrote in an initial report.

Concerns aside, further trials were organised in Humacao, Puerto Rico, and in Port-au-Prince, Haiti in 1959, before the pill was released to American consumers in 1960.

Women ignored

Despite criticism from their peers and continuous reports of the Pill's negative side effects, Pincus stood by their creation, even discounting the experiences of women who made complaints.

“These side effects are largely psychogenic. Most of them happen because women expect them," he later told the New York Times.

As more and more women went on the Pill, further side effects were also noted, including nausea, breast tenderness, water retention, weight gain and more seriously, blood clots.

In 1961, 132 incidents of thrombosis (blood clots) and embolism (when the clot blocks a blood vessel) were reported to the FDA, however because the rate of those affected (1.3 in 100,000 users) were significantly lower than women who died of pregnancy complications (36.9 in 100,000 pregnant women) these claims alarmingly went ignored.

It wouldn't be until 1978, eight years after a Senate hearing into the safety of the contraceptive pill, that the FDA introduced a risk leaflet in every pack.

The Pill today

Its problematic past aside, the Pill remains as one of the most powerful symbols of the Women's Liberation Movement, and it continues to help millions of women each day.

As Sanger, the woman who funded the trials, famously declared in 1919, "No woman can call herself free until she can choose consciously whether she will or will not be a mother," and her sentiment remains true today.

However, behind the Pill's legacy of liberation, there are the hundreds of faceless women we have to thank.

Where you aware of the dark past of birth control? Share your thoughts in a comment below.