Received: 19 September 2019
Accepted: 7 January 2020
First Online: 29 January 2020
Ethics approval and consent to participate
: This study conducted secondary analysis of anonymised data previously collected for the Demographic and Health Surveys conducted in Nigeria in 2003, 2008 and 2013 by the Monitoring and Evaluation to Assess and Use Results Demographic and Health Surveys (MEASURE DHS) project (ExternalRef removed), in conjunction with the National Population Commission of Nigeria; approval for the use of the data was granted by Measure DHS. The surveys were carried out in line with best ethical practice with two ethical review approvals: 1. Institutional Review Board of Macro International in Calverton in the United States of America and 2. National Ethical Review Committees in Nigeria. During the NDHS, information was collected confidentially after written informed consent for participation had been obtained from all the participants.
: Not applicable.
: The authors declare that they have no competing interests.