Global, regional, and national burden of preterm birth, 1990-2021: a systematic analysis from the global burden of disease study 2021.

Background: Preterm birth and its complications are leading causes of mortality among children under five years of age. Given the increasing burden of preterm birth on neonatal mortality and long-term health outcomes worldwide, a comprehensive global analysis is essential to guide effective public health interventions and policies. This study aims to assess the burden of preterm birth at the global, regional, and national levels. Methods: Using data from the Global Burden of Disease (GBD) 2021 database, this study analysed trends in age-standardized incidence rates (ASIR), age-standardized mortality rates (ASMR), and disability-adjusted life-years (DALYs) as primary outcomes for preterm birth from 1990 to 2021 at global, regional, and national levels. Data were assessed using joinpoint regression analysis, decomposition analysis, and the health inequality concentration index. Findings: Globally, the incidence, mortality and DALYs due to preterm birth have shown a declining trend, but ASIR started to increase in 2016. Males were more commonly born preterm than females (12329075.82, 95% uncertainty interval [UI]: 12192632.55-12464605.4 vs. 9224694.94, 95% UI: 9113876.1-9330107.89). Changes in DALYs were primarily due to epidemiological change (111.97%) and population (-21.59%). Low Socio-demographic Index (SDI) regions increased in annual incidence cases (43.1%, 95% UI: 40.17-46.09), while high SDI regions decreased in annual incidence cases (-9.6%, 95% UI: -11.45 to -7.79). The highest annual mortality and DALYs respectively occurred in sub-Saharan Africa (295490.66, 95% UI: 241762.78-353624.41) and South Asia (32760273.93, 95% UI: 27295547.76-39070225.69). Western sub-Saharan Africa showed the largest increase in annual incidence (98.95%, 95% UI: 94.77 to 103.09), and Australasia had the lowest annual mortality (287.18, 95% UI: 244.26-339.42) and DALYs (61081.4, 95% UI: 50897.33-73069.96). Western sub-Saharan Africa also had the highest ASMR (21.57, 95% confidence interval [CI]: 17.9-25.89). The highest ASIR (543.78, 95% CI: 535.11-553.21) and age-standardized DALYs (2064.65, 95% CI: 1717.27-2473.36) both occurred in South Asia, while the lowest ASIR and age-standardized DALYs were seen in East Asia (147.31, 95% CI: 144.22-150.85) and High-income Asia Pacific (143.32, 95% CI: 117.9-167.25). India, Nigeria, and Pakistan ranked highest globally in terms of annual incidence cases, mortality, and DALYs, while the lowest annual incidence, mortality and DALYs respectively occurred in Tokelau (2.34, 95% UI: 2.12-2.56), San Marino (0.04, 95% UI: 0.02-0.07) and Tokelau (17.22, 95% UI: 11.11-24.95). Interpretation: While the global burden of preterm birth has decreased, significant disparities persist, especially in low SDI regions. There is a need for more refined policies and preventive measures to effectively address preterm birth. Funding: No funds, grants, or other support was received.