Nobel prize-winning IVF pioneer Professor Robert Edwards, whose work led to the birth of the world's first "test tube baby", has died aged 87.
The University of Cambridge, where he was a professor, said Prof Edwards passed away peacefully in his sleep at his home just outside Cambridge.
Together with Dr Patrick Steptoe, Prof Edwards developed in vitro fertilisation, or IVF, which resulted in the birth in 1978 of the world's first test tube baby, Louise Brown.
At the time, the two were accused of playing God and interfering with nature.
Since then, the European Society for Human Reproduction and Embryology estimates that about five million babies have been born using the technique, which creates embryos in the laboratory before transferring them into a woman.
Experts say about 350,000 babies are born by IVF every year, mostly to people with infertility problems, single people and gay and lesbian couples.
"[Edwards] was an extraordinary scientist," said Dr Peter Braude, emeritus professor of obstetrics and gynecology at Kings College London, who was at Cambridge when Prof Edwards and Dr Steptoe were developing IVF.
"There was such hysteria around the kind of work he was doing," Dr Braude said, noting that Prof Edwards stopped his research for two years after he published details on how he had created embryos in the laboratory.
"He wanted to work out what the right thing to do was, whether he should continue or whether he was out on a limb," Dr Braude said.
Dr Braude said that Prof Edwards collected donor eggs from women in Oldham, where Dr Steptoe worked.
Prof Edwards then put the eggs into test tubes, which he strapped to his legs to keep them warm before catching the train to Cambridge, where he would attempt to fertilise them in the laboratory.
After Ms Brown was born, Dr Braude recalled a celebration at Cambridge, where scientists toasted Prof Edwards and Dr Steptoe's achievement by drinking champagne out of plastic cups.
Dr Braude said public opinion has evolved considerably since then.
"I think people now understand that [Edwards] only had the best motivation," he said.
"There are few biologists that have done something so practical and made a huge difference for the entire world."
In 2010, Prof Edwards was awarded the Nobel Prize in medicine or physiology for the development of IVF.
Dr Steptoe had already passed away and Nobel Prizes are not awarded posthumously.
The Catholic Church denounced the award, arguing that human life should only begin through intercourse and not artificially.
The Vatican said Prof Edwards "bore a moral responsibility for all subsequent developments in assisted reproduction technology and for all abuses made possible by IVF".
In 2011, Prof Edwards was knighted by Britain's Queen Elizabeth II "for services to human reproductive biology".
Other scientists called Prof Edwards a visionary who forever changed the lives of people helped by IVF and the medical community.
"[His] inspirational work in the early 60s led to a breakthrough that has enhanced the lives of millions of people worldwide," said Mike Macnamee, chief executive of the IVF clinic that Prof Edwards and Dr Steptoe co-founded, in a statement.
"It was a privilege to work with him and his passing is a great loss to us all."