1. Departments of Obstetrics/Gynecology (R.T.C., A.S.G., E.T.M.), Chicago, Illinois 60611
2. Physiology (R.T.C.), Chicago, Illinois 60611
3. the Robert H. Lurie Comprehensive Cancer Center (R.T.C., A.S.G., E.T.M., I.B.H., P.H.G.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
4. Preventive Medicine (I.B.H., P.H.G.), Chicago, Illinois 60611