In June 1957 something happened that was to change the lives of millions of women. Regulators in this country and the US approved a new drug which appeared to mimic pregnancy in women’s bodies, preventing ovulation. For the first time in history, women would be able to have sex without fear of an unwanted pregnancy. So it is a remarkable fact that the Pill, as it would soon become known, was not licensed as a contraceptive in the first instance.

Even more remarkably, Enovid (Enavid in the UK) was actually approved as a treatment for infertile women who were assured by its manufacturer, Searle, that it would regulate their menstrual cycles and help them get pregnant. Like almost everyone else involved in creating that first Pill, Searle knew perfectly well that Enovid’s most significant effect was to prevent pregnancy, but few dared say so. The company’s calculation was that word would quickly spread among doctors and patients, preparing the ground for the news that the world now had its first oral contraceptive.

One man who didn’t want to wait for a belated announcement was Gregory Pincus, the brilliant but maverick scientist who developed the Pill. Pincus spoke at a conference in Sweden and boasted that he had come up with “an almost 100% effective pill for preventing pregnancy”. His colleague John Rock, a Catholic doctor who had played a key role in testing the new drug, immediately despatched a telegram. “Suggest buttoning up,” Rock warned.

Pincus, Rock, and two remarkable women – the birth control pioneers Margaret Sanger and Katharine McCormick – are at the heart of this brilliant book by American journalist Jonathan Eig. It opens with a meeting in New York between Sanger and Pincus in 1950, when they discussed developing an oral contraceptive. Pincus was 47 and looked like “a cross between Albert Einstein and Groucho Marx”; Sanger was 71, worn out after spending most of her life campaigning for women’s rights, and convinced that the lack of reliable contraception was the biggest obstacle to equality. She came from a family of 11 and her mother had died of tuberculosis at 50; financial support from two of her elder sisters, who worked as a maid and a governess respectively, had allowed her to get the education they had missed.

Sanger had the arguments and the determination to drive the campaign forward but she needed scientists and a financial backer. The latter came in the shape of McCormick, who was slightly older than Sanger and recently widowed; in a chapter heading Eig characterises the two women ironically as “the socialite and the sex maniac”, reflecting the hostility of the time towards women who argued for birth control. McCormick was one of the first women to graduate with a science degree from MIT, and it was the tragedy of her personal life – her fabulously wealthy husband was diagnosed with a severe mental illness shortly after they married – that turned her towards funding medical research.

This was the 50s: in a traditional division of roles, Sanger was the advocate and McCormick the philanthropist, while men did the science. Pincus was daring, innovative and a self-publicist, a trait which cost him his grant at Harvard early in his career; he did much of his work on hormones at the Worcester Foundation, the laboratory he founded in a factory town 40 miles west of Boston. After their meeting, Sanger wrote to Pincus offering a grant of $2,000 from the Planned Parenthood Federation of America, which she had helped to found. “The amount was ludicrous,” Pincus recalled later, “but I at once replied, ‘Yes’.’

Pincus accepted because so few people were willing to be associated with his research. In retrospect, it seems an extraordinary failure on the part of mainstream scientific institutions and drug companies that they did not see the Pill’s potential. This was partly because of anxiety about the Catholic church, which – despite John Rock’s sterling efforts to argue that the Pill did not contravene doctrine – would eventually ban it altogether in 1968. But it is also a striking example of the inability of male-dominated institutions to spot what women urgently need and want. Eig quotes heartrending letters from mothers desperate not to get pregnant again, some of whom wrote directly to Pincus. A mother of six from Indianapolis wrote. “When I read this article I couldn’t help but cry, for I thought this is my ray of hope… I beg you please help me if you can.”

Pincus benefited from this neglect, carrying out hair-raising clinical trials that would not have been countenanced in mainstream institutions; he tried out his compounds on inmates of a mental hospital and a group of nursing students, who were told to take it as a requirement of starting their course, before giving it to women in the slums of Puerto Rico. Despite all the setbacks, it took only seven years to develop Enovid and have it approved for menstrual problems; three years later, in 1960, it was licensed for use as a contraceptive, a momentous piece of news which appeared on page 75 of the New York Times. Soon 400,000 American women were using it for birth control, prompting its appearance on the cover of Time magazine, which claimed it had “liberated the sex and family life of a large and still growing segment of the US population”. The magazine predicted it would one day do the same “for much of the world”, reflecting the long-held view of birth control pioneers that an oral contraceptive would solve the problem of over-population.

In the event, the Pill was adopted most enthusiastically by middle-class women who didn’t mind having to take it every day. I was one of them, taking it for the first time as a student; my generation grew up with the knowledge that we didn’t have to have children if we didn’t want to, a change so massive that Eig rightly calls it a revolution. His book often reads like a thriller as funds runs out, clinical trials stall and politicians, including John F Kennedy, shy away from the hot potato of birth control.

But Sanger never lost sight of her visionary understanding of the possibilities that would be unlocked by oral contraception; Eig’s book shows her constantly chivvying and driving the research forward, even after she suffered a series of heart attacks. For all the criticisms levelled at it in later years, the Pill’s philosophical impact has been as significant as its physical effect. Its advocates deserve this vivid and life-affirming history.

The Birth of the Pill is published by Macmillan, £14.99. Click here to buy it for £11.99