OBJECTIVE: To assess the association between gestational age at birth and the risk of growth failure and respiratory symptoms at 3 years of age. DESIGN: Cohort study using the Japan Environment and Children's Study database. PATIENTS: A total of 86 158 singleton infants born without physical abnormalities at 32-41 weeks of gestation were enrolled between January 2011 and March 2014. MAIN OUTCOME MEASURES: Growth failure (weight <
10th percentile and height <
10th percentile) and respiratory symptoms (asthma and wheezing) at 3 years of age. METHODS: Logistic regression analysis was used to evaluate the risk of growth failure and respiratory symptoms in the moderately preterm, late preterm and early term groups compared with the full-term group after adjusting for socioeconomic and perinatal factors. Multiple imputation was used to reduce the attrition bias related to missing data. RESULTS: The respective adjusted ORs (95% CI) of growth failure and respiratory symptoms for the moderate preterm, late preterm and early term groups compared with the full-term group were as follows: weight <
10th percentile, 2.29 (1.48-3.54), 1.43 (1.24-1.71) and 1.20 (1.12-1.28)
height <
10th percentile, 2.34 (1.59-3.45), 1.42 (1.25-1.60) and 1.15 (1.09-1.22)
asthma, 1.63 (1.06-2.50), 1.21 (1.04-1.41) and 1.16 (1.09-1.23)
and wheezing, 1.39 (1.02-1.90), 1.37 (1.25-1.51) and 1.11 (1.06-1.17). CONCLUSION: Moderate preterm, late preterm and early term births were associated with a higher risk of growth failure and respiratory symptoms at 3 years of age than full-term births, with an inverse dose-response pattern.