Following the publication of the original article [1], some information is missing in the Funding section and the author needs to add a Disclaimer section. The updated Funding and Disclaimer sections are given below. Disclaimer Some of the authors are present staff members of the World Health Organization. The authors alone are responsible for the views expressed in this article and they do not necessarily represent the views, decisions or policies of the institutions with which they are affiliated. Funding This work was funded by the UNDP-UNFPA-UNICEFWHO-World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), a co-sponsored programme executed by the World Health Organization (WHO). The original article [1] has been corrected.