Cognitive function at school age in children born before 27 weeks' gestation: A single-center retrospective study in...

Extremely preterm (EP) infants are at high risk of long-term neurodevelopmental impairments. School-age outcomes have been well documented in large population-based cohorts worldwide. However, data on school-age cognitive outcomes in Japanese EP populations remain limited, particularly on infants born at 22-23 weeks of gestation, whose survival has increased in Japan.

This retrospective cohort study evaluated cognitive impairments at 8 years of age in children born before 27 weeks of gestation at a single tertiary center in Japan. A total of 73 children were assessed by either the Wechsler Intelligence Scale for Children (WISC-IV or WISC-V) or Kyoto Scale of Psychological Development. Longitudinal outcomes between ages 3 and 8 were also assessed; however, due to variations in assessment tools, these changes were reported descriptively. Perinatal characteristics were compared between the gestational age groups.

Lower gestational age was associated with lower birth weight, higher incidence of chorioamnionitis, and increased rates of retinopathy of prematurity and bronchopulmonary dysplasia. The median full-scale IQ scores at 8 years were below the national average across all gestational age groups, though scores significantly increased as gestational age advanced (p = 0.001). Longitudinal analysis revealed descriptive transitions in cognitive categories; the proportion of children categorized within the normal range was 25.0% at 3 years and 51.3% at 8 years.

Children born before 27 weeks of gestation, particularly those born at 22-23 weeks, remain at risk for cognitive impairment at school age; however, cognitive outcomes significantly improved as gestational age increased. The potential for changes in cognitive categories underscores the necessity for structured, long-term follow-up programs extending into school age to support the evolving needs of this high-risk population.