Gestational-age–specific associations of fetal growth extremes with preschool sleep disturbance: a national population-based study

Sleep problems are common in preschool children, yet whether fetal growth extremes contribute to early sleep health remains unclear. We examined associations of small− and large−for−gestational−age birth(SGA/LGA) with sleep quality and sleep disturbance risk in children aged 3–5 years. We analyzed data from a population-based cross-sectional study conducted in mainland China (2018–2019) including 121 329 children aged 3−5 years with birthweight−for−gestational−age and sleep data. Birthweight−for−gestational−age was defined using national sex−and gestational−age−specific percentiles as SGA (< 10th), appropriate for gestational age (AGA) (10th–90th), or LGA (> 90th). Sleep was measured with the validated Chinese Children’s Sleep Habits Questionnaire (CSHQ), including a total score, eight domain scores, and a questionnaire−defined sleep disturbance outcome. Multilevel models with kindergarten random intercepts adjusted for maternal, child, and family covariates; prespecified subgroup were conducted, and sensitivity analyses used stricter birthweight-for-gestational-age cutoffs and an alternative CSHQ-based definition of sleep disturbance. Sleep disturbance prevalence was similar across groups (AGA: 76.2%, SGA: 77.5%, LGA: 77.2%), yet adjusted odds were slightly higher for SGA and LGA versus AGA (SGA: OR 1.05, 95% CI 1.00–1.11; LGA: OR 1.06, 95% CI 1.02–1.10). Associations differed by gestational-age strata: for LGA, odds were higher among preterm children but lower among full-term children. Sensitivity analyses using stricter fetal-growth criteria (SGA ≤3rd percentile and LGA ≥ 97th percentile) and an alternative CSHQ-based threshold(>54) for sleep disturbance showed directionally consistent associations. Secondary analyses of domain scores suggested modest elevations in several sleep domains among SGA and LGA children. SGA and LGA were modestly associated with preschool sleep disturbance, and these associations varied across gestational−age strata. Considering birthweight−for−gestational−age status within gestational−age context may help refine population−level understanding of early life factors related to childhood sleep health.