Affiliation: | 1. Obstetrics and Gynecology, New England Medical Center, Tufts University School of Medicine, Boston, MA, U.S.A.;2. Leukaemia Research Fund Centre, Institute of Cancer Research, Chester Beatty Laboratories, London, U.K.;3. Departments of Pediatrics, New England Medical Center, Tufts University School of Medicine, Boston, MA, U.S.A. Obstetrics and Gynecology, New England Medical Center, Tufts University School of Medicine, Boston, MA, U.S.A. |