Worth, born Jennifer Lee while her parents were on holiday in Clacton-on-Sea, Essex, was raised in Amersham, Buckinghamshire. After leaving school at the age of 14, she learned shorthand and typing and became the secretary to the head of Dr Challoner's Grammar School. She then trained as a nurse at the Royal Berkshire Hospital, Reading, and moved to London to receive training to become a midwife.
Lee was hired as a staff nurse at the London Hospital in Whitechapel in the early 1950s. With the Sisters of St John the Divine, an Anglican community of nuns, she worked to aid the poor. She was then a ward sister at the Elizabeth Garrett Anderson Hospital in Bloomsbury, and later at the Marie Curie Hospital in Hampstead.
She married the artist Philip Worth in 1963, and they had two daughters.
Worth retired from nursing in 1973 to pursue her musical interests. In 1974, she received a licentiate of the London College of Music, where she taught piano and singing. She obtained a fellowship in 1984. She performed as a soloist and with choirs throughout Britain and Europe.
She later began writing, and her first volume of memoirs, 'Call the Midwife', was published in 2002. The book became a bestseller when it was reissued in 2007. 'Shadows of the Workhouse' (2005; reissued 2008) and 'Farewell to the East End' (2009) also became bestsellers. The trilogy sold almost a million copies in the UK alone. In a fourth volume of memoirs 'In the Midst of Life', published in 2010, Worth reflects on her later experiences caring for the terminally ill.
Worth was highly critical of Mike Leigh's 2004 film Vera Drake, for depicting the consequences of illegal abortions unrealistically. She argued that the method shown in the movie, far from being fairly quick and painless, was in fact almost invariably fatal to the mother.
Worth died on 31 May 2011, having been diagnosed with cancer of the oesophagus earlier in the year.
A television series, Call the Midwife, based on her books, began broadcasting on BBC One on 15 January 2012.