BOSTON, Aug. 22--Dr. Gregory Goodwin Pincus, one of the three "fathers" of the birth-control pill, died here tonight at Peter Bent Brigham Hospital of myeloid metaplasia, a rare blood disease. He was 64 years old and lived in Northboro. With Dr. M. C. Chang, a senior scientist of the Worcester Foundation, and Dr. John Rock, head of the Rock Reproductive Clinic of Brookline, Mass., Dr. Pincus developed a relatively safe and simple oral contraceptive that revolutionized family planning. The Pill, as it has come to be called, not only revolutionized methods of birth control, but also introduced the previously taboo topic as a subject for worldwide debate on curbing overpopulation. Women were cautious in accepting it when it was first marketed in 1960 but today more than six million American women--nearly one-fifth of those of childbearing age--are believed to be using it--and the number is growing. Dr. Pincus was research director of the Worcester Foundation for Experimental Biology, and his interest included many aspects of hormone studies. He was an authority in mammalian reproduction and a pioneer in cancer research. In the late nineteen-forties Dr. Pincus focused his attention on the role of hormones in his study of reproduction. With a grant from the National Institute of Arthritis and Metabolic Diseases of the Public Health Service in the fifties, he began a study of the properties of hydrocortisone, an adrenal hormone. These experiments involved the use of progesterone, a female hormone secretion that is triggered by ovulation. The hormone thickens the walls of the Fallopian tubes and the womb in preparation for the fertilized egg. Progesterone also safeguards against overlapping pregnancies by preventing further fertilization and thus serves as a natural birth-control agent. Dr. Pincus and Dr. Chang began to discuss the possibility of a synthetic progesterone. They experimented with more than 200 substances before settling upon three steroid compounds derived from the roots of the wild Mexican yam. These seemed to prevent ovulation in laboratory animals. It was at this time that the two biologists teamed up with Dr. Rock, a Roman Catholic gynecologist and obstetrician, who was also working with progesterone to cure infertility in his childless patients. Dr. Chang made the basic experimental observations, while Dr. Pincus worked the findings into the over-all research scheme. "Pincus can interrupt a critical problem to take 10 phone calls and then switch his mind back to the problem in a second," an associate said. "Recognizing people and human frailties as they exist, he has freed himself from emotional turbulence." In 1956, Dr. Pincus began experiments in Brookline, Mass., Puerto Rico and Haiti with the steroids in pill form on hundreds of women. Again success was reported. In 1957 the Food and Drug Administration authorized the marketing of the steroids for miscarriage and certain menstrual disorders, and in 1960, the Federal agency licensed Enovid, a contraceptive pill. The pill is believed to be 100 per cent effective, and the very few pregnancies that have been reported among pill-users are believed to be errors in negligence in remembering to take the pill. The pill is taken daily for 20 days, during which time ovulation is impossible. The egg, instead of being released and passed into the Fallopian tubes, where fertilization could take place, is simply reabsorbed within the ovary. Within five days after the pills are stopped the woman begins to menstruate again. On the fifth day of menstruation, the next 20-day pill cycle is begun. Dr. Chang and Dr. Pincus had been working recently on a new pill, known popularly as the "morning-after" pill. It affects the egg after ovulation. During the seven days or more required for the fertilized egg to become implanted in the uterus, the pill expels the egg from the Fallopian tubes and uterus before implantation can occur. Dr. Pincus was also credited with the development of Estrone, a hormone used in the treatment of breast cancer and pregnancy complications. Dr. Pincus, a bushy-haired man with a gray mustache and dark, burning eyes, was born in Woodbine, N. J., on April 9, 1903, and later credited two uncles, both agricultural scientists, as responsible for his early interest in research. "As long as I can remember, I knew I was going to be a scientist," he once recalled. He went to Cornell and received a bachelor's degree in agriculture in 1924. Then he went to Harvard where he was an instructor in zoology while also working toward his master's and doctorate degrees. From 1927 to 1930 he moved from Harvard to Cambridge University in England to the Kaiser Wilhelm Institute in Berlin, conducting research. He became an instructor in general physiology at Harvard in 1930 and was promoted a year later to assistant professor. By 1938, at the age of 35, he was already an international authority on the sex of mammals and sex hormones, and more than 70 of his research papers had been published. Dr. Pincus became known to the general public when newspapers printed articles about his experiments and research with "fatherless" rabbits. In 1939, while a professor of experimental zoology at Clark University in Worchester, Mass., he brought about the first fatherless mammalian birth in history by inducing parthenogenesis in a female rabbit. He used high temperature, hormone treatments and salt solutions to fertilize the ovum in a test tube. He then implanted the developing egg in the reproductive tract of the female rabbit, where the egg matured through the normal stages. But the research also caused him prolonged embarrassment. In May of that year, he went to Toronto to report on his experiments to a meeting of the Federation of American Societies for Experimental Biology. He said emphatically that he was not planning to carry on his experiments with rabbits to see if human babies could be made by test-tube method. But a report of his remarks omitted the word "not," and he was thereafter called upon frequently, both here and abroad, to deny that he was trying "to create human life in the laboratory." The Worcester Foundation had been created the previous year, and Dr. Pincus and Dr. Hoagland interested local businessmen and professionals in raising funds to purchase a 12-acre estate at Shrewsbury, Mass., where the foundation's main buildings are now located. The foundation was formally incorporated in 1944, with Dr. Pincus as a co-director. The 20th anniversary report indicated some of the scope of the foundation's activities: research in the fields of steroids, cancer research, studies of the human aging process, possible chemical causes of schizophrenia and other mental diseases and the relationship of hormones to heart disease. In 1940, he was asked what he saw in the future on the basis of his early experiments. "I can't tell," he replied, "but there are no big steps, there are all little steps. We have to follow processes systematically. The big questions are: why does an egg start to develop and why does it continue to develop." Concurrent with his work at the foundation, Dr. Pincus served as research professor at the Tufts College Medical School from 1946 to 1950 and as research professor in biology at Boston University from 1950 until his death. The work of the foundation attracted eminent scientists from all parts of the world. More than 300 scientists from 40 countries are currently involved in foundation research. Dr. Pincus was a member or chairman of many important research committees of the National Institute of Health of the United States Public Health Service and also of the National Research Council. He was the recipient of numerous prizes and awards, including the Albert D. Lasker Award in Planned Parenthood, 1960; the Modern Medicine Award for Distinguished Achievement in 1964; and the American Medical Association Scientific Achievement Award in 1967. His books included "The Eggs of Mammals," published in 1936, and "The Control of Fertility," published in 1965. Dr. Pincus is survived by his widow, the former Elizabeth Notkin, whom he married in 1924; a son, John; a daughter, Mrs. Laura Bernard; three brothers, Lee, Maurice, and Alexis; a sister, Mrs. Charles O. Dutton, and four grandchildren. A funeral service will be held on Friday at 11 A.M. at Temple Emanuel, Chandler Street, Worcester. Burial will be private.