Affiliation: | aDivision of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, Pennsylvania bCenter for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania cNorthern Fertility and Reproductive Associates, Meadowbrook, Pennsylvania dDivision of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Temple University, Philadelphia, Pennsylvania |