Sex‐Specific Associations of Small, Vulnerable Newborns With Mental Capital in Early School‐Aged Children
Shuhei Terada, Aya Isumi, Takeo FujiwaraABSTRACT
Background
Although mental capital is increasingly recognised as a foundation for children's later well‐being, its perinatal determinants remain unclear because traditional classifications such as preterm birth and small for gestational age (SGA) capture only partial and overlapping aspects of vulnerability.
Objectives
Using the integrated small vulnerable newborn (SVN) framework with mutually exclusive categories, we aimed to assess associations between SVN categories and mental capital at ages 6–7 years by sex.
Methods
We analysed data from six waves of the Adachi Child Health Impact of Living Difficulty (A‐CHILD) study, a population‐based repeated cross‐sectional survey of first‐grade students in Adachi City, Tokyo, conducted between 2015 and 2024 ( n = 20,928). Caregivers provided gestational week and birthweight from the Maternal and Child Health Handbook, and children were classified into SVN categories (term non‐SGA, term SGA, preterm non‐SGA, preterm SGA). Mental capital, including behavioural problems, prosocial behaviour, and resilience, was assessed using the parent‐reported Strengths and Difficulties Questionnaire and Children's Resilience and Coping Scale. Multivariable regression models were fitted, stratified by biological sex.
Results
Among the 20,928 children, 3402 (16.3%) were term SGA, 1093 (5.2%) were preterm non‐SGA, and 227 (1.1%) were preterm SGA. Compared with term non‐SGA, term SGA was associated with higher total difficulties scores among girls (standardised β 0.11, 95% confidence interval [CI] 0.05, 0.17) but not among boys ( β 0.03, 95% CI –0.03, 0.09). Term SGA girls also showed lower resilience ( β −0.07, 95% CI –0.12, −0.01). In contrast, preterm non‐SGA boys had higher total difficulties scores ( β 0.13, 95% CI 0.04, 0.21). There was no evidence that any SVN category was associated with prosocial behaviour in either sex.
Conclusions
Term SGA tended to be associated with behavioural problems and lower resilience among girls, whereas preterm non‐SGA tended to be associated with behavioural problems among boys.