that defines viability in all clinical settings.

In modern, high-resource settings, medical viability is generally considered to be between 23 and 24 weeks' gestational age, meaning that these newborns have a <50% chance of either dying or surviving with severe impairment if active care is instituted; this applies to most fetuses at >=24 weeks of gestation, and to some fetuses at 23 weeks' gestation with favourable risk factors. Globally, among extremely preterm infants (<28 weeks' gestational age) born between 2000 and 2024, approximately 61% survived to hospital discharge, with lower survival rates in low-income countries (32%) than in high-income countries (69%).