**Author details**

Micah J. Hill *Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA* 

#### Anthony M. Propst

*Uniformed Services University of the Health Sciences, Department of Obstetrics and Gynecology, Bethesda, MD, USA* 
