1. Division of Reproductive Endocrinology and Infertility, Duke University Medical Center, 5704 Fayetteville Road, Durham, NC 27713, USA
2. Cardiovascular & Metabolic Diseases, Medical Strategy & Science, Quintiles, Inc., 5927 South Miami Boulevard, Morrisville, NC 27560, USA
3. Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC 27710, USA