3.2. Kidney Size
REGRESSION
At 6 months of age, kidney length and volume were significantly higher in the group of children fed with the higher-protein formula compared with breastfed children or those fed with the lower-protein formula. At 11 years, kidney length was larger in the higher-protein group, but volume, either absolute or adjusted for length, weight, or BMI, was similar in the three groups in the univariate analysis (To analyze the relationship between kidney volume at 11 years and feeding early in life, we conducted a linear regression analysis considering potential factors that could contribute to the determination of kidney volume (sex, birth weight, maternal smoking during pregnancy, feeding early in life, height at 11 years of age, and country). Total kidney volume at 11 years was associated with height at the same age, maternal smoking during pregnancy, and being fed with the higher-protein formula during the first year (We conducted a mediation analysis to determine if kidney volume at 6 months could be a mediator of the effect of feeding intervention in infancy on kidney volume at 11 years. The results indicate that kidney volume at 6 months significantly mediates the association of the protein formula content with a higher kidney volume at 11 years of age (HP vs. LP +6.74 cm