Dr. Middlesworth was awarded a degree in Chemistry from Dartmouth College in 1983. Following completion of his undergraduate education he spent two years in a molecular biology lab at the Children's Hospital in Boston where he played a key role in the isolation of the gene that causes Duchenne muscular dystrophy. He received his medical degree at the Robert Wood Johnson Medical School, and was trained in General Surgery at the University of Maryland.

During his surgical residency, Dr. Middlesworth spent one year as the visiting research fellow at The Royal Children's Hospital in Melbourne, Australia studying the molecular and embryologic mechanisms of testicular descent. He completed a chief residency in Traumatology at the internationally known R. Adams Cowley Shock Trauma Center before coming to the Babies and Children's Hospital of New York to train in Pediatric Surgery.

Dr. Middlesworth was appointed to the faculty of the College of Physicians and Surgeons, Columbia University in July, 1997, where he continues to pursue his interest in a broad range of pediatric surgical problems including thoracic and pancreatico-biliary diseases.