As the title of his 2018 memoir, Two Lives to Lead, hinted at, Martin Bax’s working life was split between two equally demanding duties – that of a consultant developmental paediatrician who published extensively on child disability, and founder of the long-running literary and arts magazine Ambit. Bax, who has died aged 90, also wrote fiction, while continuing his work within the NHS.

Those medical and literary interests fused with his 1976 novel The Hospital Ship, a dystopian vision showing the crew of the ironically named Hopeful tending to victims of a global mass psychosis. Text from the book was later developed, with the trumpeter Henry Lowther, into The Vietnam Symphony, performed at the ICA and on BBC Radio 3. He also published a short story collection, Memoirs of a Gone World (2010), and a children’s book, Edmond Went Far Away (1988), illustrated by the artist and Ambit contributor Michael Foreman.

Ambit, set up in 1959 from Bax’s home in Highgate, north London, and out of which it operated until his retirement in 2013, was marked from the off by a countercultural thrust, keen to place itself on the raucous margins of prevailing literary modes and fashions.

Bax spoke of the influence of John Middleton Murry’s Rhythm, the early 20th-century magazine that published DH Lawrence and Katherine Mansfield. His formative vision was to provide somewhere that visual art could speak to, and in unison with, new writing, with neither being given undue prominence. A typical issue might contain pop art, sketches, short stories and poetry. Prominent (or soon-to be) names such as the poets George MacBeth, Stevie Smith, Peter Porter and Edwin Brock found early publication in its pages. Other, established, figures such as JG Ballard and Carol Ann Duffy became regular contributors and later went on to work with Bax as editors of fiction and poetry respectively.

Ambit also boasted an impressive roll call of artists, with figures such as David Hockney and Eduardo Paolozzi contributing to its covers and pages in the 1960s. Hockney’s unfinished female nude for Ambit 14 (1962-63) was indicative of the magazine’s fondness for creating something at once playful and visually charged.

As an editor Bax struck out for a sort of radical independence – all the more radical for his not buying into some of the more political or polemical angles then being taken up by his contemporaries, such as Michael Horovitz, whose more Beat-inflected New Departures was founded the same year. Bax said: “What was my programme? … Well, I don’t really have a programme; I just put good things together.”

During the mid-to-late 60s, boundaries of explicitness and provocation began to be tested more committedly than in the magazine’s first decade. In response to a Ballard story, You: Coma: Marilyn Monroe, published in Ambit 27 (1966), a note from a Conservative MP to the then-minister of state for education and science hints, in its Mary Whitehouse fashion, at the ways in which the magazine had evolved: “[Ambit] is disgusting when it is possible to understand the words used. Some of it seems to be the product of a twisted mind. If it gets into the hands of teenagers, as it easily could, it would be a most dangerous publication.”

Undeterred, in 1967, the magazine ran a competition “for the best creative work, both prose and poetry, written under the influence of drugs”. Despite the inevitable furore, the winner – the experimental novelist Ann Quin – wasn’t much of a cautionary tale to the nation’s youth, being “under my usual combination of nicotine, [caffeine] and of course, the birth pill I take – Orthonovin 2”.

Born in Walton-on-Thames, Surrey, Bax was the son of Cyril, a civil servant, and Eleanor (nee Bayne), a former domestic science teacher. Public service – and social concern – ran through the paternal line, with Bax’s grandfather, Ernest Belfort Bax, a founder member of the Fabian Society and associate of William Morris.

He went to Dauntsey’s school, Wiltshire, then studied medicine at New College, Oxford, and Guy’s hospital, where, following graduation in 1961, he became a lecturer at its medical school.

At Oxford Bax met Judy Osborn, and they married in 1956. She went on to work as a headteacher at Parliament Hill school in north London and after her retirement won a seat on Haringey council.

Bax worked as a paediatrician in the NHS throughout his career, specialising in child development and disability. He was an especially influential figure in the treatment of cerebral palsy in children. From 1982 to 1985 he was director of the Community Paediatric Research Unit at St Mary’s hospital medical school, then at Westminster hospital medical school (now part of Imperial College School of Medicine), where he was also a senior lecturer and, after retirement in 2001, emeritus reader.

He was editor of the journal Developmental Medicine and Child Neurology from 1978 after the death of Ronnie MacKeith, his longstanding colleague who founded the journal and with whom Bax had helped to set up the Clinics in Developmental Medicine book series. From 2000 to 2008 he served as chairman of the European Academy of Child Disability, and he was life president of the Society for the Study of Behavioural Phenotypes.

Bax published a final novel, Love on the Borders, in 2005. The breadth of his achievements in both the medical and the literary worlds is evidence of his ability to adapt and innovate, to push boundaries with his hunger for finding what was new and unexpected.

Ambit’s origins as a home-made, DIY magazine set by hand on a variotyper were somewhat unpromising for the kind of longevity it would ultimately achieve. It continued publishing until 2023, becoming one of the UK’s longest-running periodicals.

Judy died in 2015. Bax is survived by his three sons, Ben, Alex and Tim, seven grandchildren and one great-grandchild.

• Martin Charles Owen Bax, consultant paediatrician, novelist and editor, born 13 August 1933; died 24 March 2024