1. Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
2. Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA, USA
3. Department of Obstetrics and Gynecology, Magee-Women's Research Institute, Pittsburgh, PA, USA
4. Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA
5. Department of Health and Human Development, School of Education, University of Pittsburgh, Pittsburgh, PA, USA
6. Department of Epidemiology and Biostatistics, School of Public Health, University of West Virginia, Morgantown, WV, USA