1 Department of Public and Occupational Health, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, 1105AZ, Netherlands. Electronic address: f.p.chilunga@amsterdamumc.nl.
2 Developmental Pathways for Health Research Unit, University of Witwatersrand, Johannesburg, South Africa.
3 Department of Population, Family and Reproductive Health, School of Public Health, University of Ghana, Accra, Ghana.
4 Department of Paediatrics, Muhimbili National Hospital, Dar Es Salaam, Tanzania.
5 Department of Public Health, Section of Health Services Research, University of Copenhagen, Copenhagen, Denmark.
6 Malawi Intervention and Epidemiology Research Unit, Lilongwe, Malawi.