1. Department of Family Medicine, University of Michigan, Ann Arbor, Michigan.
2. Undergraduate student, University of Michigan, Ann Arbor, Michigan.
3. School of Public Health, University of Michigan, Ann Arbor, Michigan.
4. Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan.
5. Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.