Dr. Jenyons earned her medical degree from Dartmouth Medical School in New Hampshire, and trained in obstetrics and gynecology at St. Luke's-Roosevelt Hospital Center. She is board-certified in obstetrics and gynecology, and she has been an attending physician at St. Luke's-Roosevelt since 1995. In 2001, she joined the faculty; she also served as director of the hospital center's Washington Heights Women's Health Center from 2001until 2006.

From 1996 until 2001, Dr. Jenyons was director of obstetrics and gynecology at New York Presbyterian Hospital's Allen Pavilion. She directed the Obstetrics Teen Clinic at St. Luke's Hospital from 1982 until 1985, and has spent almost 20 years in private practice in New York City. During that time, she has been an active participant in women's health education, especially in the city's Latina and Dominican communities. She was president of the Dominican Medical Society, and is a fellow of the American College of Obstetricians and Gynecologists.

Dr. Jenyons has given numerous women's health lectures to the public and to practitioners. She is interested in alternative or complementary approaches to gynecologic conditions and to the management of menopause. She supports alternative methods of pain relief during labor, such as hypnosis, massage, and hydrotherapy (labor in a Jacuzzi). She supports labor and birth in Roosevelt's special Birthing Center, as a patient option in low-risk deliveries.