Louise Brown was born at Oldham and District General Hospital at 11.47 p.m. on 25 July 1978. She was the first child born after being conceived through in vitro fertilisation.

Her mother, Lesley Brown, had been unable to conceive because her Fallopian tubes were blocked. This prevented an egg from travelling towards the womb and meeting sperm in the usual way.

IVF offered a route around the blockage. An egg could be removed from an ovary, fertilised outside the body and allowed to begin developing before being transferred to the womb.

The treatment resulted from work by Robert Edwards, Patrick Steptoe and Jean Purdy. Edwards studied human fertilisation and early embryo development. Steptoe was a gynaecologist experienced in laparoscopy, which allowed eggs to be collected from the ovaries. Purdy worked throughout the laboratory and clinical programme and became one of the first clinical embryologists.

The three had worked together for about ten years. Their records show hundreds of attempted egg collections and fertilisations, but few pregnancies. Some attempts failed because an egg was not collected or fertilised. Others ended after an embryo had been transferred.

In November 1977, Steptoe collected an egg from Lesley Brown. It was fertilised with sperm from her husband, John. Purdy was the first member of the team to see the embryo dividing. The embryo was transferred to Lesley’s womb, and the pregnancy continued to term.

Louise was delivered by Caesarean section. She weighed 5 lb 12 oz and was healthy.

The birth attracted international press attention. Reports often called Louise the first ‘test-tube baby’. However, only the earliest stage of her development had taken place outside her mother’s body.

Her birth established that IVF could result in a healthy child. Other clinics began offering the treatment. Edwards, Steptoe and Purdy helped establish Bourn Hall, the first specialist IVF clinic, in 1980.

The technique also raised questions about the status of embryos, the limits of research and the control of fertility clinics. The government established an inquiry chaired by Mary Warnock. Its 1984 report recommended legal limits and an independent regulator.

Parliament passed the Human Fertilisation and Embryology Act in 1990. The Human Fertilisation and Embryology Authority began regulating British fertility clinics and embryo research the following year.