(CNN) -- Sir Robert Edwards, a "co-pioneer" of the in vitro fertilization technique and Nobel Prize winner, died Wednesday in his sleep after a long illness, the University of Cambridge said. He was 87.
Edwards, a professor at the university and fellow of Churchill College, Cambridge, and Dr. Patrick Steptoe developed the fertility treatment, which involves fertilizing an egg outside the womb and implanting the newly created embryo inside a woman's uterus.
Their work resulted in the birth of Louise Brown on July 25, 1978 -- the world's first "test-tube baby."
Since then, an estimated 5 million babies have been born worldwide thanks to IVF, according to the International Committee for Monitoring Assisted Reproductive Technologies, an international nonprofit organization.
When Brown married in 2004, Edwards attended the wedding. Steptoe died in 1988.
Edwards was awarded the Nobel Prize in Physiology or Medicine in 2010 for his work in developing the technique. The next year, he was knighted "for services to human reproductive biology," the university said in a statement.
Both Edwards and Steptoe faced intense publicity and criticism from those opposed to the method, including the Vatican, after Brown's birth, according to the statement.
"Bob Edwards is one of our greatest scientists," said Mike Macnamee, chief executive of Bourn Hall, the IVF clinic Edwards and Steptoe co-founded, in the statement. "His inspirational work in the early '60s led to a breakthrough that has enhanced the lives of millions of people worldwide. He is held in great affection by everyone who has worked with him and was treated by him."
Dr. Linda C. Giudice, president of the American Society of Reproductive Medicine, said in a statement that Edwards "was a great scientist whose stellar scientific work advanced our understanding of human reproduction, human embryonic stem cells, advanced pre-implantation genetic diagnosis and revolutionized the treatment of infertility.
"We extend our condolences to his family, and his many friends around the world."