1. Divisions of Reproductive and Child Health (K.J.B., M.D.K.), Birmingham B15 2TT, United Kingdom
2. Medical Sciences (C.J.M., F.L.K., J.A.F.), The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
3. School of Clinical and Laboratory Science (J.N.B.), University of Newcastle, Newcastle upon Tyne NE1 4LP, United Kingdom
4. Department of Biochemistry and Immunology (G.S.J.W.), St. George’s Hospital Medical School, London SW17 0RE, United Kingdom