INTRODUCTION: Older gestational age (GA) has been associated with more favourable cognitive outcomes in preterm children. Recent evidence suggests this may also apply to term-born children. This study aims to examine the association between GA and early neurodevelopmental outcomes in children born at term in China and the UK. METHODS: Participants were term-born children from two cohorts, the Sichuan Multi-stratified Infants and Early Life (SMILE) study in China and the Developing Human Connectome Project (dHCP) in the UK. Early cognitive outcomes were assessed at 6 months in the SMILE study, and at 18 months in the dHCP. Linear regression models were conducted to examine the association between GA at birth and early cognitive outcomes in each cohort separately. RESULTS: A sample of 1245 participants from the SMILE study and 406 participants for the dHCP were included in the analysis. In the SMILE study, longer GA was associated with better mental developmental (B = 2.47 [1.60, 3.34], P <
.001) and psychomotor outcomes (B = 2.91 [2.01, 3.82], P <
.001), after controlling for sex, parental education, family yearly income, maternal age, maternal depressive symptoms, and birth weight
in the dHCP, longer GA was associated with better cognitive (B = 1.35 [0.33, 2.37], P = .010) and motor outcomes (B = 1.49 [0.59, 2.39], P = .001), after controlling for sex, relative social deprivation, maternal depressive symptoms and birth weight. CONCLUSIONS: Older GA in term-born toddlers is associated with more favourable developmental outcomes across different cultural contexts.