1 Department of Obstetrics & Gynecology, University of California Los Angeles, Los Angeles, CA.
2 University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
3 Department of Obstetrics and Gynecology, University of Pennsylvania Perelman School of Medicine, 800 Spruce St., 2 Pine East, Philadelphia, PA 19107; Leonard Davis Institute of Health Economics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA. Electronic address: Rebecca.feldmanhamm@uphs.upenn.edu.