1. Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh (J.V.Z., J.A.C., E.O.T.), Pittsburgh, Pennsylvania 15261
2. Department of Obstetrics and Gynecology, University of Rochester School of Medicine (D.S.G.), Rochester, New York 14642
3. Division of Endocrinology and Metabolism, University of Louisville Health Sciences Center (S.J.W.), Louisville, Kentucky 40292