Association of infant weight gain patterns with early childhood obesity among infants born small or large for gestational age

To characterize weight gain patterns in small-for-gestational age (SGA) and large-for-gestational age (LGA) infants during the first year and examine their associations with childhood overweight and obesity risk. Infants in a Taiwan national cohort (April 2016–June 2017) were assessed at 3, 6, 12, and 36 months of age. Patterns of weight-for-age Z-scores (WAZ) were classified, and their association with obesity risk at age 36 months was analyzed. There were 499 SGA, 389 LGA, and 3890 appropriate-for-gestational age (AGA) infants with complete records up to 36 months of age. The prevalence of overweight or obesity at age 36 months was 5.2% in the SGA group (overweight: 3%; obesity: 2.2%), 8.1% in the AGA group (overweight: 5.9%; obesity: 2.2%), and 14.6% in the LGA group (overweight: 10%; obesity: 4.6%). The prevalence of being underweight was 6.4%, 1.9%, and 0.3% in the SGA, AGA, and LGA groups, respectively. We identified four weight gain patterns for each birth weight category. An accelerated growth pattern was associated with increased obesity risk in all three groups. Compared with the group with stable growth pattern, SGA infants with WAZ change (△WAZ) > 1.88 had a 2.41-fold increased risk (95% CI: 0.99, 5.88) of overweight/obesity, whereas LGA infants with △WAZ > 1.21 had a 10.79-fold increased risk (95% CI: 4.33, 26.90). Among children classified as being with overweight/obesity at 3 years old by BMI-for-age, mean weight-for-height Z-score (WFHZ) was 2.75 ± 0.95 (78.79% with WFHZ > 2); among those with obesity, mean WFHZ was 3.92 ± 0.93 (100% with WFHZ > 2), confirming concordance between BMI- and WFH-based adiposity classification. Avoiding accelerated weight gain patterns across all birth weight categories may help decrease the risk of later obesity. Additionally, the influence of constitutional genetic factors that result in naturally small or large body phenotypes should be considered to ensure growth assessments are individualized and appropriate.