NEURODEVELOPMENTAL OUTCOMES OF THE TINIEST BABIES

Care of preterm infants with extremely low birth weight (BW) and having intact survival is still a challenge for Neonatologists. In this issue study reported the survival rate and the outcome of preterm infants with a BW of ≤500 g in a single institute during a 10-year period. Their strategy regarding the timing of delivery of live or stillborn infants with a BW of ≤500 g is to deliver cases where continued pregnancy would compromise maternal health or where non-reassuring fetal status is identified.

The survival rate was 80% among live births, and the results of developmental assessments of 3-year-old children were 29% normal, 43% mild disability, and 29% severe disability.  All the tiniest babies were also the most immature ones, and they would die if they did not receive any resuscitation or life support after birth. The approach regarding the care of the most immature babies varies around the world.  In Japan, the limit of viability as defined in the law is 22 completed weeks of gestation. Preterm babies with a gestational age of ≥22 weeks will be resuscitated and admitted to the intensive care unit.  The differences in the approaches related to the most immature babies result in the variation of survival rates in different countries and regions.

When counselling with parents, both survival rate and long-term neurodevelopmental outcomes are important for decision-making in the management of the most immature or the tiniest babies. A systematic review and meta-analysis focusing on neurodevelopmental outcomes of the most immature babies demonstrated that the most commonly observed neurodevelopmental disability is cognitive impairment, followed by cerebral palsy.  Vision and hearing deficits occur less frequently.  In Japan, the new Kyoto Scale of Psychological Development (KSPD) test was used for neurodevelopmental evaluation. Study reported that 43% (3/7) of survived patients had mild neurodevelopmental disability. One patient was diagnosed with autism spectrum disorder with a normal DQ at the age of 3 years. In addition, 42% of the survived patients had either visual or hearing impairment. Hence, concerns remain regarding the neurodevelopmental outcomes of preterm infants with a BW of ≤500 g.

Improving the survival rate of very tiny preterm infants and preventing the adverse neurodevelopmental outcomes are of utmost importance. One of the important therapies for the tiny preterm infants is the administration of antenatal corticosteroids (ANCS). Among the live births with a BW of ≤500 g, there was only one mother who received ANCS in the study. The administration of ANCS for an impending preterm delivery before 25 weeks of gestation is a controversial issue. A recent meta-analysis study showed reduced mortality and intraventricular hemorrhage (IVH) or periventricular leukomalacia in neonates born at <25 weeks and exposed to ANCS. There was no difference in the occurrence of stage II or more of necrotizing enterocolitis (NEC), and the incidence of chronic lung disease (CLD) was higher in the group that was administered ANCS. Composite outcomes of death or major morbidities (severe IVH, NEC, or CLD) were improved after exposure to ANCS. With the improvement of perinatal care, the survival rate of the most immature and the tiniest babies has increased. Further larger and additional long-term follow-up studies as well as further research on the management of the tiniest babies are needed to guide decision-making and to prevent major morbidities and disabilities.