Sex Differences in Survival Chances Among Children, Adolescents, and Youth Ages 0–24: A Systematic Assessment of National, Regional, and Global Trends from 1990 to 2021

Abstract

Background: Differences in survival chances exist between sexes due to biological factors and sex discrimination, which are well documented in children younger than 5. However, sex differentials in mortality have not been systematically examined for ages 5–24 based on empirical data.

Methods: We estimate the sex ratio of mortality from birth to 25 and reconstruct trends in sex-specific mortality between 1990 and 2021 for 200 countries, major regions, and globally. We compiled comprehensive databases on the sex ratio of mortality (ratio of male to female mortality rates) for infants (<1 year), young children (1–4 years), older children and young adolescents (5–14 years), and older adolescents and youth (15–24 years). The databases contain mortality rates from (sample) death registration systems, surveys collecting full birth and sibling histories, and reports on recent household deaths in censuses and nationally representative surveys. We adjusted mortality rates for the incompleteness of death registration for each sex and accounted for recall biases. In each age group, the sex ratio of mortality was modelled as a function of the mortality level achieved for both sexes using Bayesian hierarchical time series models. We report on the levels and trends of sex ratios and estimate the expected and excess female mortality rates to identify countries with outlying sex ratios.

Findings: Globally, the sex ratio of mortality was 1·13 for ages 0–4 years [90% uncertainty interval (UI) 1·11–1·15] in 2021. This ratio increases with age to 1·16 [90% UI 1·12–1·20] for those 5–14 years old, reaching 1·65 for 15–24 years old [1·52–1·75]. In all age groups, the global sex ratio of mortality increased between 1990 and 2021, driven by faster declines in female mortality. In 2021, the probability of a male newborn reaching his 25th birthday was 94·1% [93·7%–94·4%], compared to 95·1% for girls [94·7%–95·3%]. A disadvantage of girls to boys (compared to countries with similar total mortality levels) in 2021 was observed in five countries for ages 0–4 (Algeria, Bangladesh, Egypt, India, and Iran), one country (Suriname) for ages 5–14, and 13 countries for ages 15–24 (including Bangladesh and India). The reverse pattern (significant disadvantage of boys to girls) was observed in one country in children ages 0–4 (Vietnam), no country in the age group 5–14, and eight countries in youth ages 15–24 (including Brazil and Mexico). Globally, the total number of excess female deaths from birth to 25 was 86,563 [-6,059–164,000] in 2021, from 544,636 [453,982–633,265] in 1990.

Interpretation: Globally, the sex ratio of mortality for all age groups before 25 increased between 1990 and 2021. The survival chances to age 25 improved more rapidly for girls than boys as total mortality decreased, reversing this trend at very low mortality. Targeted interventions should focus on countries with outlying sex ratios of mortality.

Funding Information: This study was supported by the Bill & Melinda Gates Foundation, United States Agency for International Development, and King Abdullah University of Science and Technology.

Declaration of Interests: We declare no competing interests.

Keywords: under-25 mortality rate, sex disparity, sustainable development goals, Bayesian modeling