Dr. Louis Gluck, 73, a pioneer in neonatal and perinatal care. In 1960, Gluck established the first neonatal intensive care unit in the world at Yale University. Nine years later, he set up a similar unit at UC San Diego Medical Center. In 1984, he moved to UC Irvine Medical Center as head of neonatology and professor of pediatrics, obstetrics and gynecology. Born in Newark, N.J., Gluck was educated at Rutgers University and the University of Chicago School of Medicine. He taught at Stanford before going to Yale. In 1971, he developed the "L/S ratio," a procedure to determine fetal lung maturity and whether a baby will undergo respiratory distress during birth. Gluck, who edited more than a dozen professional journals and wrote more than 300 medical articles, even assisted newborn animals at the San Diego Zoo and Wild Animal Park during his 15 years in San Diego. On Saturday in Laguna Hills of pancreatic cancer.