The limit of viability for premature newborns has changed in recent decades, but whether
to initiate or withhold active care for periviable infants remains a subject of debate
because the chances of survival and the extent of severe neurological impairment can
be unclear. In our review, we analyzed large population-based studies of periviable
infants from the past 2 decades. We compared survival rates and the incidence of early
complications among survivors, including bronchopulmonary dysplasia, intraventricular
hemorrhage, periventricular leukomalacia, retinopathy of prematurity, and necrotizing
enterocolitis. Moreover, we assessed the perinatal factors that may affect the survival
of preterm infants. We analyzed 15 studies reporting data on preterm infants born
between 22 and 28 gestational weeks. None of these studies reported survival of an
infant born before 22 gestational weeks. Survival rates of infants born at 24 weeks'
gestation were above 50% in most studies. The incidence of each complication was also
higher among infants born at <= 24 weeks. Of the analyzed perinatal factors, antenatal
corticosteroid therapy, birth weight, female sex, cesarean delivery, singleton pregnancy,
and birth in a tertiary-level Neonatal Intensive Care Unit were found to be associated
with improved survival in some studies. The different methodologies of the studies
limited comparison of the results. Further investigations are needed to gain up-to-date
information on the limit of viability, and standardized methods in future studies
would enable more accurate comparisons of findings.
