1. Liggins Institute (F.H.B., M.H.O., P.H., P.D.G., J.E.H.), University of Auckland, Auckland 1020, New Zealand
2. Departments of Physiology and Obstetrics and Gynaecology (F.H.B., A.C.H., M.C., J.R.G.C.), University of Toronto, Toronto, Ontario, Canada M5S 1A8