1 MRC Centre for Reproductive Health, University of Edinburgh, Edinburgh, UK.
2 FIGO Menstrual Disorders Committee, Los Angeles, CA, USA; Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, University of California Los Angeles, Los Angeles, CA, USA.
3 Clinical Trials Unit, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK.
4 Clinical Trials Unit, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK. Electronic address: ian.roberts@lshtm.ac.uk.