Houston. His investigative pursuits center on reproductive genetics: prenatal genetic diagnosis and preimplantation genetics, genetics of spontaneous abortion, elucidation of disorders of sexual differentiation, and determination of the causes of chromosomal nondisjunction. Dr. Simpson was 1993-1994 president of the American Society for Reproductive Medicine, 1994-1998 president of the International Society of Prenatal Diagnosis, 1995-1998 president of the Society for Advancement of Contraception, and 1998-1999 president of the Society for Gynecologic Investigation. He is a member of the March of Dimes Scientific Advisory Board and was a member from 1995 to 1997 of the National Institute of Child Health and Human Development Advisory Council. In 1995 he was elected to the Institute of Medicine. He is treasurer or the American College of Medical Genetics, and has assumed many responsibilities for the American College of Obstetricians and Gynecologists. He has published extensively in the fields of obstetrics and gynecology, clinical genetics, and etiology of birth defects. Dr. Simpson has received major research funding from the March of Dimes, the National Institutes of Health, and the U.S. Agency for International Development.