Author Contributions: Mr Özaltin had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Özaltin, Hill, Subramanian.
Acquisition of data: Özaltin.
Analysis and interpretation of data: Özaltin, Hill, Subramanian.
Drafting of the manuscript: Özaltin, Subramanian.
Critical revision of the manuscript for important intellectual content: Özaltin, Hill, Subramanian.
Statistical analysis: Özaltin, Hill.
Administrative, technical, or material support: Subramanian.
Study supervision: Subramanian.
Financial Disclosures: None reported.
Funding/Support: No direct financial support or funding was obtained to conduct this study. Dr Subramanian is supported by a career development grant NHLBI K25 HL081275 from the National Institutes of Health.
Role of the Sponsor: The National Institutes of Health and Macro International Inc did not participate in the design and conduct of the study, in the collection, analysis, and interpretation of the data, or in the preparation, review, or approval of the manuscript.
Additional Contributions: Macro International Inc, Washington, DC, provided access to the various Demographic and Health Surveys. David Canning, PhD (Economics and International Health, Harvard University, Boston, Massachusetts), and Christopher Murray, MD, DPhil (Institute for Health Metrics and Evaluation, University of Washington, Seattle), provided helpful discussions on the manuscript. Drs Canning and Murray did not receive any compensation for their contributions.