Introduction: Personalized medicine: what is it and what are the challenges?

Personalized medicine and precision medicine are presenting new opportunities for better patient care, but also present unique challenges. The traditional randomized clinical trial is not necessarily the most appropriate approach to evaluating what may be the best treatment for an individual. Alternative study designs pose unique regulatory challenges for the U.S. Food and Drug Administration but offer the opportunity for higher response rates. Ovarian stimulation for assisted reproductive technology offers opportunities for personalized and more precise approaches to individual patient care.