We aimed to quantify the relationship between national income and infant and under-five mortality in developing countries.

We conducted a systematic literature search of studies that examined the relationship between income and child mortality (infant and/or under-five mortality) and meta-analysed their results.

Developing countries.

Child mortality (infant and /or under-five mortality).

The systematic literature search identified 24 studies, which produced 38 estimates that examined the impact of income on the mortality rates. Using meta-analysis, we produced pooled estimates of the relationship between income and mortality. The pooled estimate of the relationship between income and infant mortality before adjusting for covariates is –0.95 (95% CI –1.34 to –0.57) and that for under-five mortality is –0.45 (95% CI –0.79 to –0.11). After adjusting for covariates, pooled estimate of the relationship between income and infant mortality is –0.33 (–0.39 to –0.26) while the estimate for under-five mortality is –0.28 (–0.37 to –0.19). If a country has an infant mortality of 50 per 1000 live births and the gross domestic product per capita purchasing power parity increases by 10%, the infant mortality will decrease to 45 per 1000 live births.

Income is an important determinant of child survival and this work provides a pooled estimate for the relationship.