B. Lo
V. Chou, and L. Wolf are in the Program in Medical Ethics;M. I. Cedars, E. Gates, and R. N. Taylor are in the Department of Obstetrics, Gynecology, and Reproductive Sciences;R. M. Wagner is in the Human Subjects Protection Program;K. R. Yamamoto is in the Department of Cellular and Molecular Pharmacology; all are at the School of Medicine at the University of California, San Francisco, CA 94143, USA.