1. UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, WHO, CH–1211 Geneva 27, Switzerland
2. Centro Rosarino de Estudios Perinatales (CREP), WHO Collaborative Center in Maternal and Child Health, Rosario 2000, Argentina
3. Geneva Foundation for Medical Education and Research, Geneva, Switzerland
4. Department of Nutrition, WHO, CH–1211 Geneva 27, Switzerland