1. Pregnancy Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research , Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, United States Department of Health and Human Services, Bethesda, Maryland , and Detroit , MI , USA
2. Department of Obstetrics and Gynecology , University of Michigan , Ann Arbor , MI , USA
3. Department of Epidemiology and Biostatistics , Michigan State University , East Lansing , MI , USA