6805 Impact of Feeding Types on Catch-Up Growth in Early Infancy Among Small-for-Gestational-Age Infants: A Nationwide Korean Study

Abstract Disclosure: J. Choi: None. Y. Choe: None. S. Yang: None. Purpose: The study aimed to compare growth patterns and catch-up growth (CUG) in small-for-gestational-age (SGA) infants up to age four, based on feeding type during the first 4-6 months, using nationwide data. Methods: A total of 42,295 children born SGA (21,917 boys, 52.%) who underwent the first (4-6 month), 2nd (9-12 month), 3rd (18-24 month) and 5th (42-48 month) National Health Screening Program for Infants and Children (NHSPIC) under the National Health Insurance Service from 2007 to 2014 were included. The study population was categorized into two groups based on the primary milk feeding type recorded in the self-reported questionnaire during the first round of NHSPIC: the ”Breastfed”group, and the "Formula-fed" group. Catch-up growth (CUG) was defined as a Height Standard Deviation Score (Ht SDS) of 3rd percentile or above at the 5th NHSPIC visits. We used propensity scores to 1:1 match breastfed and formula-fed group based on sex, birth weight, cesarean section, socioeconomic status, residance. Multivariate logistic regression analysis was performed to evaluate the effect of milk feeding type on CUG at 4 years of age. Results: 49.1% of infants (n = 20,774) were breastfed and 50.9% (n = 21,521) were formula-fed. The median birth weight was 2.7 kg (interquartile range: 2.5-2.9 kg), and 98.7% of the children (n = 41,752) achieved CUG by the 5th NHSPIC round. Following propensity score matching, both groups included 19,308 infants. At four years of age, the breastfed group showed a lower likelihood of achieving CUG compared to the formula-fed group (aOR 0.794, 95% CI 0.665-0.948). During the 1st NHSPIC round, the breastfed group had a significantly lower weight Z-score (mean: -0.05, range: -0.64 to 0.41) than the formula-fed group (mean: 0.14, range: -0.42 to 0.78, p < 0.001). This trend was more pronounced from the 1st to 2nd round, with greater decreases in both weight and height Z-scores for the breastfed group (weight difference: -0.36, range: -0.74 to 0.02; height difference: -0.21, range: -0.62 to 0.20) compared to the formula-fed group (weight difference: -0.17, range: -0.53 to 0.20; height difference: -0.13, range: -0.53 to 0.28, p < 0.001). However, from the 2nd round, the breastfed group demonstrated faster gains in both weight and height (p < 0.001). Conclusion : In a study of Korean SGA infants, those breastfed during the first 4-6 months post-birth had lower CUG rates at four years compared to formula-fed infants. The breastfed group exhibited less weight and height gain, especially between the 1st and 2nd NHSPIC rounds, aligning with the initial phase of solid food introduction. These findings may suggest the need for enhanced nutritional supplementation for breastfed SGA infants. Further research is necessary to explore other factors that may impact growth during this critical developmental period. Presentation: 6/3/2024