1 Department of Reproductive Health and Research, UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland. Electronic address: amina@who.int.
2 Department of Population, Family and Reproductive Health, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland.
3 Department of Reproductive Health and Research, UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland; Adolescent Health Unit, Institute of Child Health, University of Ibadan, Ibadan, Nigeria.
4 Department of Reproductive Health and Research, UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland.