1. Health Systems Based on Primary Health Care (HSS), Pan American Health Organization; Research Promotion and Development Team; 525, 23rd St, NW Washington DC USA 20037-2895
2. The University of Liverpool; Cochrane Pregnancy and Childbirth Group, Department of Women's and Children's Health; First Floor, Liverpool Women's NHS Foundation Trust Crown Street Liverpool UK L8 7SS
3. Pan American Health Organization (PAHO/WHO); Research Promotion Team and Development; 525 23rd St NW Washington DC USA 20037-2895
4. Fundación Santa Fe de Bogotá; Maternal and Fetal Medicine - Obstetrics and Gynecology; Clle 119 N 7 - 75 Bogotá Cundinamarca Colombia 571