1. Children’s Hospital of Philadelphia and the Department of Pediatrics (M.B.L., S.M.-M., J.M.B., M.T., L.K., R.J.W., B.S.Z.), Philadelphia, Pennsylvania 19104
2. Department of Epidemiology and Biostatistics (M.B.L., J.S.), University of Pennsylvania, Philadelphia, Pennsylvania 19104
3. Department of Epidemiology and Biostatistics (A.E.), George Washington University School of Public Health and Health Services, Washington, D.C. 20037