1. From the Center for Health Research, Kaiser Permanente Northwest (T.A.H., K.L.P., K.K.V., J.V.M.), and the Division of Perinatology, Department of Obstetrics and Gynecology, Northwest Permanente, Kaiser Permanente (S.L.L.), Portland, Oregon; and the Center for Integrated Health Care Research (T.A.H., C.E.S.O.) and the Division of Perinatology, Department of Obstetrics and Gynecology (K.K.O.), Hawaii Permanente Medical Group (K.L.P., K.K.O.), Kaiser Permanente Hawaii, Honolulu.