1. Department of Reproductive Medicine and Gynecology (N.S.M., B.C.J.M.F.), University Medical Center Utrecht, 3508 GA Utrecht, The Netherlands;
2. Division of Reproductive Sciences (R.L.S.), Oregon National Primate Research Center, Oregon Health & Science University, Portland, Oregon 97239-3098;
3. Department of Obstetrics and Gynecology (L.C.G.), Stanford University School of Medicine, Stanford, California 94305