[1] Univ Edinburgh, MRC Ctr Reprod Hlth, Edinburgh, Scotland
[2] Kamuzu Univ Hlth Sci, Ctr Reprod Hlth, Blantyre, Malawi
[3] Kamuzu Univ Hlth Sci, Dept Obstet & Gynaecol, Blantyre, Malawi
[4] Malawi Epidemiol & Intervent Res Unit, Lilongwe, Malawi
[5] Univ Liverpool, Inst Life Course & Med Sci, Fac Hlth & Life Sci, Liverpool, England
[6] Univ Edinburgh, Usher Inst, Ctr Med Informat, Edinburgh, Scotland
[7] Univ Bristol, Fac Hlth Sci, Bristol, England
[8] Univ Edinburgh, Ctr Cardiovasc Sci, Edinburgh, Scotland
[9] Borders Gen Hosp, NHS Borders, Melrose, Scotland
[10] Univ Liverpool, Inst Infect Vet & Ecol Sci, Fac Hlth & Life Sci, Liverpool, England