BMI trajectories from ages 1 to 7 years and associated cardiometabolic risk at age 8 years: distinguishing cumulative and timing-specific effects.

BACKGROUND: Evidence from repeated early-childhood BMI measurements in Chinese children remains limited. This study aimed to examine associations between body mass index (BMI) trajectories from ages 1 to 7 years and cardiometabolic risk at age 8 in this population, and to further distinguish cumulative and timing-specific effects of early BMI development. METHODS: We followed 1072 mother-child pairs from Tianjin, China for 8 years. Height and weight were measured annually between ages 1 and 7 years; blood pressure, fasting glucose, and lipid concentrations were assessed at age 8. Group-based trajectory modeling was used to identify BMI trajectories. Excess BMI-years, adiposity rebound (AR) age, and interval-specific conditional BMI Z-score gain at ages 1-3, 3-5, and 5-7 years were further assessed. Generalized linear and logistic regression models were used to estimate associations with a modified continuous cardiometabolic risk score (modified cMetS) and cardiometabolic risk traits (CRTs) at age 8. RESULTS: Two adverse BMI trajectories were identified: late obesity growth pattern (LOGP) and persistent obesity growth pattern (POGP). Compared with control trajectory, LOGP and POGP were associated with higher modified cMetS in fully adjusted models [LOGP: regression coefficient (β) = 0.88, 95% confidence interval (CI) = 0.53-1.22; POGP: β = 1.59, 95% CI = 0.87-2.31] and higher CRT risk [LOGP: odds ratio (OR) = 1.70, 95% CI = 1.20-2.41; POGP: OR = 3.91, 95% CI = 1.92-7.99]. Among individual CRT components, significant associations were mainly observed for hypertension. Greater excess BMI-years, earlier AR, and greater conditional BMI Z-score gain during ages 3-5 and 5-7 years were also associated with higher modified cMetS and CRT risk. CONCLUSIONS: LOGP and POGP in early childhood were associated with increased cardiometabolic risk at age 8. Greater cumulative excess BMI burden, earlier AR, and accelerated BMI gain during specific periods may help identify children at higher risk.