Limits of viability: are we heading in right direction?

Background The limits of viability, commonly defined by gestational age and/or birth weight thresholds associated with a survival probability exceeding 50 %, have evolved with advances in neonatal care. However, these thresholds vary substantially across countries, reflecting differences in health system capacity rather than fixed biological boundaries. ContentThis review critically examines the definition of the limits of viability as a context-dependent construct shaped by access to perinatal and neonatal care. It analyzes global disparities in survival at the margins of prematurity, with marked differences between high-income (HIC) and low- and middle-income countries (LMIC). These inequities are discussed within the framework of the Sustainable Development Goals (SDG), particularly SDG 3 and SDG 10, and in relation to the child's right to the highest attainable standard of health. The role of global health governance, including the World Health Organization (WHO), and emerging challenges affecting international collaboration are also considered. Current trends in both HIC and LMIC are evaluated to assess alignment between technological progress and global health equity.SummaryThe limits of viability are not fixed biological thresholds but reflect health system capacity. Persistent disparities in periviable survival remain substantial and result in outcomes determined largely by place of birth rather than biological potential.OutlookReducing inequities requires prioritizing equitable implementation of evidence-based interventions, strengthening health systems, and sustaining global collaboration. Aligning advances in neonatal care with global equity is essential to improving outcomes for the most vulnerable newborns.