Department of Biostatistics, University of Nebraska Medical Center, Omaha, 68198-4350, NE, USA. fangyu@unmc.edu.|Department of Statistics, University of Connecticut, Storrs, 06269-4120, CT, USA. ming-hui.chen@uconn.edu.|Department of Statistics, University of Connecticut, Storrs, 06269-4120, CT, USA. lynn.kuo@uconn.edu.|Department of Biochemistry and Molecular Biology and Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, 68198-5870, NE, USA. heather.talbott@unmc.edu.|VA Nebraska-Western Iowa Health Care System and Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, 68198-3255, NE, USA. jsdavis@unmc.edu.