1. From the University Department of Pathological Biochemistry (N.S., D.O.R.) and Department of Obstetrics and Gynaecology (I.A.G.), Glasgow Royal Infirmary, Glasgow, UK; the University Department of General Practice (A.M., M.U., G.W.), University of Glasgow, UK; and the Department of Social Medicine (G.D.S., M.U.), University of Bristol, Canynge Hall, Bristol, UK.