Socioeconomic inequalities in the prevalence of underweight, overweight, and obesity among women aged 20-49 in low- and middle-income countries

Objective To analyze socioeconomic inequalities in the prevalence of underweight and overweight or obesity in women from low and middle-income countries (LMICs). Methods Using the last available Demographic Health Survey between 2010 and 2016 from 49 LMICs, we estimated the prevalence of underweight (BMI < 18.5 kg/m(2)) and overweight or obesity combined (BMI >= 25 kg/m(2)) for women aged 20-49 years. We used linear regression to explore the associations between the two outcomes and gross national income (GNI). We assess within-country socioeconomic inequalities using wealth deciles. The slope index of inequality (SII) and the inequality pattern index (IPI) were calculated for each outcome. Negative values of the latter express bottom inequality (when inequality is driven by the poorest deciles) while positive values express top inequality (driven by the richest deciles). Results In total, 931,145 women were studied. The median prevalence of underweight, overweight or obesity combined, and obesity were 7.3% (range 0.2-20.5%), 31.5% (8.8-85.3%), and 10.2% (1.9-48.8%), respectively. Pearson correlation coefficients with log GNI were -0.33 (p = 0.006) for underweight, 0.72 (p < 0.001) for overweight or obesity, and 0.66 (p < 0.001) for obesity. For underweight, the SII was significantly negative in 38 of the 49 countries indicating a higher burden among poor women. There was no evidence of top or bottom inequality. Overweight or obesity increased significantly with wealth in 44 of the 49 countries. Top inequality was observed in low-prevalence countries, and bottom inequality in high-prevalence countries. Conclusion Underweight remains a problem among the poorest women in poor countries, but overweight and obesity are the prevailing problem as national income increases. In low-prevalence countries, overweight or obesity levels are driven by the higher prevalence among the richest women; as national prevalence increases, only the poorest women are relatively preserved from the epidemic.