BackgroundChild undernutrition remains a major global health issue, particularly in sub-Saharan Africa (SSA). Given the important role mothers play in early childhood health and development, we examined how individual-level women’s empowerment and country-level Gender Inequality Index (GII) are jointly related with child undernutrition in SSA. MethodsWe pooled recent Demographic and Health Surveys from 28 SSA countries. For 137,699 children <5 years old, undernutrition was defined using anthropometric failures (stunting, underweight, wasting). Women’s empowerment was assessed using three domains of Survey-based Women’s EmPowERment (SWPER) index: attitude to violence, social independence, and decision-making; and country-level gender inequality was measured using GII from United Nations Development Programme. Three-level logistic regression was conducted to examine the joint associations of SWPER and GII as well as their interactions with child anthropometric failures, after adjusting for sociodemographic covariates. ResultsOverall, 32.85% of children were stunted, 17.63% were underweight, and 6.68% had wasting. Children of mothers with low-level of empowerment for all domains of SWPER had higher odds of stunting (attitude to violence: OR=1.15; 95% CI, 1.11-1.19; social independence: OR=1.21; 95% CI, 1.17-1.25; decision-making: OR=1.16; 95% CI, 1.12-1.20), and consistent results were found for underweight and wasting. Independent of women’s empowerment, country-level GII increased the probability of underweight (ranging ORs=1.46; 95% CI, 1.15-1.85 to 1.50; 95% CI, 1.18-1.90) and wasting (ranging ORs=1.56; 95% CI, 1.24-1.97 to 1.61; 95% CI, 1.27-2.03). Significant interaction was found between women’s empowerment and country-level GII for stunting and underweight (p<0.05). ConclusionsIn SSA countries with greater gender inequality, improving women’s social independence and decision-making power in particular can reduce their children’s risk of anthropometric failures. Policies and interventions targeted at strengthening women's empowerment should consider the degree of gender inequality in each country.