Association between small for gestational age and neurodevelopmental disability at 5 years in the Hokkaido study

Background Low birth weight is a known risk factor for delayed growth and disability in children. It is assessed using a measure called small for gestational age (SGA). SGA children have an increased risk of neurodevelopmental disabilities, regardless of gestational age. We conducted this study to evaluate the effects of SGA on neurodevelopmental disability, particularly in SGA full‐term newborns (term‐SGA). Methods This study was conducted using a prospective birth cohort from the Hokkaido Study on Environment and Children's Health. The mothers of 4851 children who reached the age of 5 years between April 2008 and November 2011 received questionnaires, including the strengths and difficulties questionnaire (SDQ). Neurodevelopmental disability was assessed using the SDQ. SGA infants, including term‐SGA, were assessed by referring to the birth weight database of the Japan Pediatric Society. Results We received 3484 responses from the parents. Univariate analysis revealed a significant difference in hyperactivity/inattention and the total difficulties score (TDS) between groups defined as normal and borderline/clinical based on the TDS, for both SGA and term‐SGA infants. In the multivariate analysis, sex, household income, and SGA and term‐SGA status were significantly associated with TDS (term‐SGA: odds ratio [OR] = 1.72; 95% confidence interval [CI], 1.07–2.76; SGA, OR = 1.75; 95% CI: 1.10–2.78). However, SGA and term‐SGA status were not associated with hyperactivity/inattention. Conclusions SGA, even at term, may predispose children to neurodevelopmental disability.