1. Division of Maternal-Fetal Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
2. Department of Obstetrics and Gynecology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
3. Department of Maternal and Child Health, Carolina Global Breastfeeding Institute, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
4. Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
5. Center for Developmental Science, Chapel Hill, North Carolina.
6. School of Education, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.