Variations in country-specific sex ratios at birth

A study finds natural variation in baseline sex ratios at birth and evidence of sex ratio inflation in 12 countries. Prevalence of sex-selective abortion in some countries can skew the sex ratio at birth, but quantifying the degree of sex ratio inflation in a country is complicated by a lack of baseline data for individual regions around the world and uncertainty associated with observations. Fengqing Chao and colleagues compiled vital registration, census, and survey data from 202 countries, including 10,835 observations, to estimate sex ratio at birth for all countries between 1950 and 2017. Regionally, baseline sex ratios were heterogeneous and deviated from the previous standard baseline male-to-female ratio of 1.05, with Sub-Saharan Africa exhibiting a baseline ratio of 1.031 and Oceania exhibiting a ratio of 1.067. Examining the time-series data, the authors found 12 countries in which the sex ratio displayed imbalance since 1970. The countries included India and China, as well as eastern Asian countries, such as the Republic of Korea, central Asian countries, such as Azerbaijan, and Eastern European countries, such as Albania. Taken together, the skewed sex ratios represent around 23.1 million missing female births between 1970 and 2017, the majority in China, with 11.9 million missing females, and in India, with 10.6 million missing females. According to the authors, the results demonstrate the need to track sex ratio at birth and its natural variations worldwide.

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Article #18-12593: "Systematic assessment of the sex ratio at birth for all countries and estimation of national imbalances and regional reference levels," by Fengqing Chao, Patrick Gerland, Alex R. Cook, and Leontine Alkema.

MEDIA CONTACT: Fengqing Chao, National University of Singapore, SINGAPORE; tel: +65 82822897; e-mail: <chao.fengqing@gmail.com>

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