Convergence in maternal mortality ratios: evidence and implications for SDG 3.1

BACKGROUND: Since 2000, the world has achieved notable progress in reducing maternal mortality, though regional disparities remain pronounced. These uneven outcomes raise critical questions about whether countries are collectively converging toward the Sustainable Development Goal (SDG) 3.1 target of fewer than 70 deaths per 100,000 live births by 2030, or diverging into distinct clusters marked by persistent inequality. METHOD: This study employs Gini coefficient decomposition and kernel density estimation (KDE) to quantify regional differences and trace the evolving distribution of maternal mortality ratios (MMRs) across 163 countries from 1990 to 2023. A convergence model is then applied to analyze long-run dynamics. Specifically, recognizing that the Phillips-Sul framework overlooks spatial dependence and mobility between clubs, the Local Directional Moran Scatterplot (LDMS) methodology is adopted, situating each country in Moran space and modeling trajectories as random vector fields (RVF). RESULTS: The findings show that: (1) Global maternal mortality fell consistently from 1990 to 2023, with distributions shifting lower. COVID-19 briefly widened disparities, but recovery by 2023 confirmed continued progress. (2) The global MMR Gini coefficient remained persistently high, averaging about 0.66, with inter-regional disparities as the primary source of inequality. (3) Countries are not converging along a single universal path but instead into three distinct clubs. By 2030, forecasts indicate that out of 163 countries, 65 (40%) will achieve the SDG 3.1 target, while 98 (60%) will remain above the threshold. CONCLUSIONS: This divergence highlights the urgent need for stronger health systems, socio-economic empowerment, and global partnerships to help lagging countries overcome entrenched high MMR trajectories.