Dr. Klein is an accomplished board-certified reproductive endocrinologist and assistant professor of Obstetrics, Gynecology, and Reproductive Science at the Icahn School of Medicine at Mount Sinai. He earned his medical degree at Harvard University, completing his residency in Obstetrics, Gynecology and Reproductive Biology at Massachusetts General and Brigham & Women’s Hospitals. He did his fellowship in Reproductive Endocrinology and Infertility at Columbia University and is board-certified in Obstetrics and Gynecology as well as Reproductive Endocrinology and Infertility.

Dr. Klein practiced for several years at one of the largest academic IVF programs in the US, where he served as medical director for Reproductive Medicine Associates of New York in Brooklyn. Most recently, he co-founded Extend Fertility, the first and only egg freezing service to focus exclusively on women proactively preserving their fertility.

Dr. Klein has authored and co-authored publications in leading peer-reviewed academic journals such as Science, Fertility and Sterility, and Obstetrics and Gynecology. He has also written numerous chapters for medical textbooks and has presented research at national conferences including the American Society for Reproductive Medicine (ASRM). Dr. Klein sits on the medical board of several fertility advocacy organizations and regularly gives lectures and presentations to community groups on infertility and fertility preservation. Dr. Klein has been recognized as a New York Super Doctors Rising Star for several years.