1 UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, Department of Reproductive Health and Research, WHO, 1211 Geneva 27, Switzerland. Electronic address: vogeljo@who.int.
2 UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, Department of Reproductive Health and Research, WHO, 1211 Geneva 27, Switzerland.
3 Department of Maternal, Newborn, Child and Adolescent Health, WHO, 1211 Geneva 27, Switzerland.