Early Life Neurodevelopment of Infants Across a Wide Gestational Age Range.

Objective: Neural development differs between in-utero and ex-utero environments. Length of gestational age (GA) is associated with brain development and early life neurodevelopmental outcomes, affecting both preterm and term infants. This study aimed to examine a wide range of GA and provide a more comprehensive understanding of its effects on various developmental domains.

Method: Four hundred fifty-four infants who were born at 24 to 41 weeks of GA were included in this analysis. Cognitive, language, and motor development between 8 and 30 months of age were assessed using the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Associations between GA and outcomes were analyzed using linear and logistic mixed-effects models.

Results: GA was positively associated with all examined developmental domains with a small-sized effect (Pearson's correlation coefficients: 0.08-0.15; p < 0.05). After adjusting for covariates, linear mixed-effect models estimated that each additional week of GA was associated with an increase in Bayley III composite scores: cognitive (0.6 points), language (0.6 points), and motor (0.62 points). Logistic mixed-effect models showed that after adjusting for the covariates, each additional week of GA reduced the adjusted odds ratio of delay in 1 of the language subdomains (i.e., receptive communication) by 13%.

Conclusion: We found a small impact of GA on cognitive, language, and motor development across a wide range of GA. Language and its subdomains seem particularly sensitive to the effects of prematurity. Thus, regular monitoring and parent-based early intervention, especially in the language domain, are warranted for early-term and preterm infants.