LIMITS OF VIABILITY: SHOULD WE PLAY GOD?

Aim is to show that the definition of the infants born at the limits of viability within the countries is dependent on the social and medical conditions in which the infant is born, and even in one country in which neonatal intensive care is available, it depends on the place of birth and organization of perinatal care. With decreasing gestational age mortality, short- and long-term morbidity of preterm infants are increasing while their survival to discharge is decreasing. It is questionable how to define viability and where the limit of viability can be set. The definition of the limits of viability is not quite clear. There are at least two ways of understanding it: the first, defining the gestational age and/or birth weight at which human fetus has the capability of survival outside the uterus; and the second, gestational age and/or birth weight at which more than 50% of infants survive to discharge home from the hospital. While in developing countries infants of less than 28 weeks of gestation without neonatal intensive care have 95% probability of dying, survival of infants between 22 and 25 gestational weeks in developed countries is reaching 90%. Up to now the definition of the limits of viability has not be established, and precise definition of viability scientifically has not been produced yet. Currently, the World Health Organization sets lower limit of viability at 22 weeks of gestation, or 500 g birth weight, or 25 cm of birth length. The universal definition of the limit of viability is probably not possible, because of its variability from one individual to the other, from one setting to the other and from one community to the other.