Neurodevelopment in full-term small for gestational age infants: A nationwide Japanese population-based study

Objective: To investigate neurological development in small for gestational age (SGA) infants, with a focus on full-term SGA infants. Methods: We analyzed data from a large, Japanese, nationwide, population-based longitudinal survey started in 2001. We restricted the study to participants born before 42 weeks of gestation (n = 46,563). Parents were asked questions about motor and language development when the children were 2.5 years old, and about behavioral development at 5.5 years. We analyzed the relationships between SGA status and development by logistic regression. Odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated for each outcome for full-term and preterm births, adjusting for potential infant- and parent-related confounding factors. We also calculated the population-attributable fractions to estimate the public impact of SGA births. Results: SGA full-term children were more likely to demonstrate developmental delays at 2.5 years, e.g., being unable to walk alone (OR 3.0, 95% CI: 1.7, 5.3), compose a two-phrase sentence (OR 1.5, 95% CI: 1.2, 1.8), or use a spoon to eat (OR 1.5, 95% CI: 1.1, 1.9). SGA status also had some degree of negative impacts on behavioral problems at 5.5 years among term children, e.g., being unable to listen without fidgeting (OR 1.2, 95% CI: 1.1, 1.3), or remain patient (OR 1.1, 95% CI: 1.0, 1.2). The public health impacts were comparable between full-term and preterm SGA children at 2.5 years. Conclusion: SGA is a risk factor for developmental delay, even in full-term infants, with non-negligible public health impacts.