1. Ibis Reproductive Health, Cambridge, MA 02142, USA
2. Department of Chronic Disease Epidemiology, Yale School of Public Health, New Haven, CT 06520, USA
3. General Internal Medicine, Yale School of Medicine, New Haven, CT 06520, USA
4. School of Nursing, The University of the Virgin Islands, St. Thomas 00802, U.S. Virgin Islands
5. Faculty of Medical Sciences, The University of the West Indies, Cave Hill, Bridgetown P.O. Box 64, Barbados
6. Medical Sciences Campus, The University of Puerto Rico, San Juan 00921, Puerto Rico
7. Faculty of Medical Sciences, The University of the West Indies, St. Augustine, St. Augustine, Trinidad and Tobago