The Nobel Prize in physiology or medicine has been awarded this year to Robert G. Edwards, an English biologist who, with a physician colleague, Patrick Steptoe, developed the in vitro fertilization procedure for treating human infertility.Since the birth of the first test tube baby, Louise Brown, on July 25, 1978, some four million babies worldwide have been conceived by mixing eggs and sperm outside the body and returning the embryo to the womb to resume development. The procedure overcomes many previously untreatable causes of infertility.Dr. Edwards, a physiologist who spent much of his career at Cambridge University in England, spent more than 20 years solving a series of problems in getting eggs and sperm to mature and successfully unite outside the body. His colleague, Dr. Steptoe, was a gynecologist and pioneer of laparoscopic surgery, the method used to extract eggs from the prospective mother.Dr. Steptoe, who presumably would otherwise have shared the prize, died in 1988. Dr. Edwards, who born in 1925, has now retired as head of research from the Bourn Hall Clinic in Cambridge, which he and Dr. Steptoe founded as the world's first center for in vitro fertilization.Though in vitro fertilization is now widely accepted, the birth of the first test tube baby was greeted with intense concern that the moral order was subverted by unnatural intervention in the mysterious process of creating a human being. Dr. Edwards was well aware of the ethical issues raised by his research and took the lead in addressing them.The objections gradually died away, except on the part of the Roman Catholic Church, as it became clear that the babies born by in vitro fertilization were healthy and that their parents were overjoyed to be able to start a family. Long-term follow-ups have confirmed the essential safety of the technique.The deliberations of the prize-giving committee at the Karolinksa Institute in Sweden are confidential, and it is unclear why it took so long to acknowledge Dr. Edwards's achievement.The committee routinely ignores the stipulation in Alfred Nobel's will that the prize should be awarded for a discovery made the preceding year, because it takes longer than that to evaluate most scientific claims, but delays of 30 years or more are unusual. The Lasker Foundation in New York, whose jurors often anticipate the Nobel Prize committee, awarded Dr. Edwards its prize in 2001.Dr. Edwards's research proved too controversial for the Medical Research Council, a government financng agency that is the British equivalent of the National Institutes of Health. In 1971 the council rejected an application from Dr. Edwards and Dr. Steptoe to work on in vitro fertilization, but they were able to continue with private funds.

"In retrospect, it is amazing that Edwards not only was able to respond to the continued criticism of in vitro fertilization, but that he also remained so persistent and unperturbed in fulfilling his scientific vision," Christer Höög, a member of the Nobel Prize committee, writes on the Nobel Foundation's Web page.