The National Childbirth Trust began with two births: one an easy delivery for an unnamed young girl in the East End of London around a century ago, and the other a stillbirth for a woman called Prunella Briance, several decades later. The two mothers never met, but their stories were connected by a doctor whose inspiration led Briance, who has died aged 91, to found the NCT.

He was Grantly Dick-Read, a GP from Suffolk, who became committed to helping women make childbirth an easier and more fulfilling experience. Shortly before the outbreak of the first world war, as a young doctor, he attended a birth in an impoverished area of the East End. The young woman was offered pain relief, but refused. The child was born safely, and afterwards Dick-Read asked the mother why she hadn’t wanted drugs. “It didn’t hurt,” the woman replied. “It wasn’t meant to, was it, doctor?”

That exchange became the cornerstone of Dick-Read’s philosophy: fear, he decided, heightened the pain of childbirth and it led to tension, which led to pain. Of course labour was painful, but what made it excruciating was a lack of information and a feeling of powerlessness. He expanded his ideas in the book Revelation of Childbirth (1942), later republished and better known as Childbirth Without Fear, and when Briance became pregnant with her second child in the early 1950s, she turned eagerly to Dick-Read’s book and to his ideas.

It was her second delivery: two years earlier she had given birth to a son, in Cyprus, by caesarean section, in the middle of a power cut. At one point Briance, who had been given a local anaesthetic, overheard the nurses saying she might not make it. Now back in London, her second delivery was to be even more traumatic – she was given castor oil, which made her sick, a midwife dropped her while helping her on to the delivery bed, and the baby got stuck. The baby, a girl, was born dead, which devastated Briance, as it would any mother.

These experiences of childbirth could have dissuaded Briance of any idea that the experience of childbirth could be improved for women, still less the notion that it could be improved by giving women more information, and encouraging them to make their own decisions supported by, rather than instructed by, obstetricians. Instead, they strengthened her resolve to work for something better. On 4 May 1956, she placed an advertisement in the personal column of the Times: “A Natural Childbirth Association is to be formed for the promotion and better understanding of the Dick-Read system.”

Over the days and weeks that followed, Briance was inundated with letters and messages of support from women who realised that their voices, and their experiences, were being excluded from decision-making around childbirth, and who knew it was time for change. In those days, what happened in the delivery room was barely discussed. In the 240 pages of one of the few manuals of the time, the Sunday Express Baby Book (1950) by Ada Anna Woodman, there was one solitary paragraph about what the reader could expect of the birth itself. “In the delivery room, white with bright lights, you will be taken from the hospital trolley to the delivery table,” it said. “The nurses will be standing by with the doctor and with their gentle help and encouragement, aided by the science they have studied so long, your baby will be born.”

There was so much more to know, and women realised it. In January 1957 the inaugural meeting of the new organisation was held at a packed Caxton Hall in Westminster. Its first stated aim was “that women should be humanely treated during pregnancy and in labour, never hurried, bullied or ridiculed”. Other ambitions included the hope that husbands would be admitted to the delivery room, and that the need for routine episiotomy, internal examinations and analgesia should be questioned.

Dick-Read had made a film on natural childbirth, also entitled Childbirth Without Fear, and the Natural Childbrith Association, as it then was, organised regular screenings, and began to run antenatal classes – a chance to educate women in what to expect in childbirth, as well as to socialise with other parents-to-be.

Today, 60 years on, the NCT – the NCA was renamed the Natural Childbirth Trust in 1958 and three years later the National Childbirth Trust – is the UK’s largest charity for parents and has 332 branches across the country, helping many thousands through pregnancy, birth and early parenthood each year. In the intervening period it has been criticised for being too middle-class, and for being too focused on “natural” childbirth, but through the 70s and 80s it campaigned vociferously, and sometimes successfully, against the over-medicalisation of birth. Today’s attitude that women are partners in their own care through pregnancy and birth owes a great deal to the NCT, its early leaders and their objectives.

Briance was born in London, the daughter of Eric Chapman, an officer in the Indian army, and his wife, Vera, a former prima ballerina. During Prunella’s early life she lived in India. During the second world war she was a signaller in the Wrens, and later became an air hostess. She met John Briance while both were studying Russian at London University and they married in 1950; he was a diplomat, posted to Persia (Iran), Washington and Singapore, as well as Cyprus.

An optimistic and joyful character who bubbled with enthusiasm, Prunella was a natural leader of the NCT. But in the years following its inception there were sometimes arguments between her and others about the best way forward. She remained an indefatigable defender of the rights of women to information around birth. In her later years, during which she continued to be active – she was an enthusiastic artist, discovered a passion for singing in her 40s, and played tennis – she was again close to the organisation she had founded, and of which she was deservedly proud.

John died in 1989. Prunella is survived by her son, Richard, and daughter, Alison.

• Prunella Mary Briance, childbirth campaigner, born 31 January 1926; died 14 July 2017