Affiliation: | 1. Department of Obstetrics and Gynecology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire;2. Mass-General Hospital for Children, Harvard Medical School, Boston, Massachusetts;3. Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, Michigan;4. Department of Community Health Sciences, Boston University School of Public Health, Boston, Massachusetts;5. Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts;6. Bureau of Family Health and Nutrition, Massachusetts Department of Public Health, Boston, Massachusetts |