1. a Department of Population, Family and Reproductive Health , The Bill and Melinda Gates Institute, Johns Hopkins Bloomberg School of Public Health , Baltimore, MD, USA
2. b Department of Community Health, Faculty of Clinical Sciences , Obafemi Awolowo University , Ile-Ife, Nigeria
3. c Department of Community Health, Faculty of Medicine , Addis Ababa University , Addis Ababa, Ethiopia
4. d Centre for Population and Reproductive Health, College of Medicine , University of Ibadan , Ibadan, Nigeria
5. e School of Medical Sciences , Kwame Nkrumah University of Science and Technology , Kumasi, Ghana
6. f Centre for Reproductive Health, College of Medicine , University of Malawi , Blantyre, Malawi
7. g School of Public Health, College of Health Sciences , University of Ghana , Legon, Accra, Ghana