Previously, he was in private practice in Springfield (1972-2000) and on the volunteer teaching staff at SIU (1972-2000).
Oh earned his medical degree from the College of Medicine at Yonsei University in Seoul, Korea (1963). He completed his obstetrics and gynecology residency at Bridgeport Hospital in Bridgeport, Conn. (1971) and a one-year fellowship in endocrinology at Harlem Hospital in New York City (1972).
He is board certified by the American Board of Obstetrics and Gynecology and is a fellow of the American College of Obstetricians & Gynecologists. He is a member of the American Fertility Society.
A naturalized American citizen, Oh is married to Kyung Oh and has two children.