Global trends, projections, and inequalities in neonatal sudden infant death syndrome mortality attributable to risk factors from 1990 to 2021.

BACKGROUND: Sudden infant death syndrome (SIDS) remains a leading cause of infant mortality. The neonatal period, as a distinct stage within infancy, has been a focus due to its associated mortality burden. We evaluated the global mortality burden and temporal trends of neonatal SIDS attributable to each risk factor from 1990 to 2021, assessed socioeconomic inequalities across these risk factors, and projected these trends through 2035. METHODS: Data on neonatal SIDS deaths and the proportions attributable to risk factors were obtained from the Global Burden of Disease (GBD) 2021 study. Temporal trends in mortality rates were assessed using the average annual percent change (AAPC), socioeconomic inequalities were evaluated using the slope index of inequality (SII) and the concentration index, and future mortality burden through 2035 was projected using autoregressive integrated moving average (ARIMA) models. RESULTS: Behavioral risks, child and maternal malnutrition, and low birth weight and short gestation were the leading contributors to neonatal SIDS mortality, with the burden concentrated in lower sociodemographic index (SDI) regions. Between 1990 and 2021, mortality attributable to these risk factors declined globally but remained unevenly distributed across socioeconomic groups. Inequality analyses indicated a persistent concentration of deaths in disadvantaged settings. Projections to 2035 suggest continued declines for most risk factors, although environmental risks may decrease more slowly. CONCLUSIONS: SIDS in the neonatal period remains a major global health challenge, particularly in low-SDI regions. Interventions targeting behavioral risks, child and maternal malnutrition, and low birth weight and short gestation are urgently needed.