1. Cincinnati Children's Center for Breastfeeding Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
2. Center for Biobehavioral Health, The Research Institute at Nationwide Children's Hospital Medical Center, Columbus, Ohio.
3. Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, Ohio.
4. Department of Microbiology, College of Arts and Sciences, The Ohio State University, Columbus, Ohio.
5. Department of Pediatrics, College of Medicine, The Ohio State University, Columbus, Ohio.
6. Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital Medical Center, Columbus, Ohio.
7. Division of Epidemiology, College of Public Health, The Ohio State University, Columbus, Ohio.