National and regional Temporal trends and forecasting of preterm birth in brazil: evidence from National birth data (2014-2023) with projections to 2030.

BACKGROUND: Preterm birth (PTB) remains one of the leading causes of neonatal morbidity and mortality globally. In Brazil, regional disparities and socioeconomic inequalities significantly affect maternal and perinatal outcomes. This study aims to describe national and regional trends in preterm birth in Brazil from 2014 to 2023, examine sociodemographic disparities, and forecast future rates through 2030 using time-series analysis. METHODS: We conducted a population-based ecological analysis using data from the Brazilian Live Birth Information System (SINASC) from 2014 to 2023. PTB was defined as delivery before 37 completed weeks of gestation. Descriptive statistics were employed to explore maternal, obstetric, and neonatal characteristics. Temporal trends were assessed using Prais-Winsten regression to estimate Annual Percentage Change (APC) and Average Annual Percentage Change (AAPC) at a significance level of 5%. A national monthly time series was constructed using Forecasting models, including Seasonal Autoregressive Integrated Moving Average (SARIMA) and Generalised Autoregressive Conditional Heteroskedasticity (GARCH). RESULTS: The analysis included over 25.5 million live births. The national prevalence of PTB increased from 11.3% in 2014 to 11.9% in 2023, with an AAPC of 0.28% (95% CI: 0.43 to 1.00; p < 0.001). Higher rates were consistently observed among those without a formal education (15.1%). Regional disparities were evident, with the highest rates among mothers aged ≥ 35 years (13.6%) and those aged < 20 years (12.8%), as well as among those in the North (12.2%) and Northeast (11.5%) regions. SARIMA modelling indicated a continued upward trajectory through 2030. In contrast, more educated women (≥ 12 years) are expected to maintain lower and stable rates (< 13%). CONCLUSIONS: PTB rates in Brazil have shown a rising trend over the past decade, with marked regional and social inequalities. Forecasts indicate that these disparities may increase by 2030 unless effective, evidence-based, and context-specific interventions are implemented. These findings highlight the urgent need for targeted public health policies and prenatal care strategies aimed at reducing preventable PTB and promoting maternal and neonatal equity across the country.