A Systematic Assessment of National, Regional and Global Levels and Trends in the Sex Ratio at Birth and Identification of Countries with Outlying Levels

Abstract

Under normal circumstances, the sex ratio at birth (SRB) has been reported to vary between 1.04 and 1.07. But gender discrimination and other factors associated with the SRB can result in different SRB levels. While SRB estimates have been published for various countries and periods, a systematic assessment of SRBs for all countries over time using all available data and reproducible estimation methods has not been reported to date. In this paper, we estimated country-specific SRBs for 212 countries and areas from 1990 to 2013 using a Bayesian hierarchical time series model and assessed the uncertainty in SRBs. The analysis is based on an extensive database with national-level data, including data from vital registration systems, international and national survey programs. We present results for countries and areas and identify country-years with SRBs which differ significantly from estimates that are typical for the country-specific region.