Global Burden of Lower Respiratory Infections Attributable to Suboptimal Breastfeeding in Infants Under 6 Months: An Analysis of the Global Burden of Disease Study 1990–2021

<b><i>Background:</i></b> Lower respiratory infections (LRIs) are a leading cause of death in young children. Exclusive breastfeeding provides essential protection in early infancy, yet suboptimal practices remain common. This study assessed the global burden of LRIs attributable to suboptimal breastfeeding in infants under 6 months between 1990 and 2021 across 204 countries and territories. <b><i>Methods:</i></b> Using Global Burden of Disease 2021 data, we assessed LRI-related deaths, disability-adjusted life years (DALYs), and age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) attributable to suboptimal breastfeeding in infants under 6 months, defined as any nonexclusive breastfeeding. Temporal trends were assessed by estimating annual percentage changes (EAPCs) with 95% confidence intervals (CIs), and associations with the sociodemographic index (SDI) were examined via Spearman correlation. <b><i>Results:</i></b> In 2021, suboptimal breastfeeding accounted for 37,890 (95% uncertainty interval [UI]: 21,011-55,423) LRI-related deaths and 3.41 million (95% UI: 1.89-4.98 million) DALYs. From 1990 to 2021, global ASMR declined from 268.25 (95% UI: 150.00-396.23) to 59.71 (95% UI: 33.11-87.34) per 100,000 (EAPC: -4.31%, 95% CI: -4.54 to -4.08) and ASDR from 24,104.89 (95% UI: 13479.26-35602.58) to 5,366.53 (95% UI: 2975.75-7849.25) (EAPC: -4.31%, 95% CI: -4.54 to -4.08). In 2021, the burden peaked in the low-SDI quintile; Western Sub-Saharan Africa had the greatest regional burden, and Chad ranked the highest nationally. <b><i>Conclusions:</i></b> Although the global LRI burden from suboptimal breastfeeding has decreased substantially, it remains concentrated in low-SDI settings. Promoting early initiation and exclusive breastfeeding, alongside strengthened maternal-child health services, is essential to reducing preventable infant mortality.