Relation between Birth Weight and Weight and Height at the Age of 2 in Children Born Preterm

The aim of the study was to evaluate associations between fetal growth and weight at 2 years in infants born preterm using a customized approach for birth weight.This is a secondary analysis of a multicenter trial that included a 2-year follow-up of children born prematurely. Customized birth weight percentiles were calculated using the Gardosi model for a U.S. population, and the relation between customized percentile and weight and height at 2 years (adjusted for gender using z-score) was determined using regression analysis and by comparing z-scores for children with birth weight10th versus ≥10th percentile.Weight z-score at 2 years was significantly lower in the10th than in the ≥10th percentile group (median [interquartile range, IQR]: -0.66 [-1.58, -0.01] vs. -0.23 [-1.05, 0.55]; p 0.001), and remained after adjusting for maternal education (p 0.001). A similar relationship was noted for height z-score between groups (median [IQR]: -0.56 [-1.29, 0.19] vs. -0.24 [-0.99, 0.37]; p 0.001). Positive relationships between customized birth weight percentile and weight and height at 2 years were noted (p 0.001 for both), but were not strong (R (2) = 0.04 and 0.02, respectively).Customized birth weight percentile is a minor determinant of weight at 2 years among children born preterm.