Relationships between IGF-I and Weight Z Score, BMI, Tricipital Skin-Fold Thickness, Type of Feeding in Healthy Infants in the First 5 Months of Life

Abstract

Aim: To determine the concentration of insulin-like growth factor-I (IGF-I) in exclusively breast-fed (BF) and formula-fed (FF) infants in the first 5 months of life and to study the relationship between the IGF-I level and Z score for weight, body mass index (BMI) and tricipital skin-fold thickness. Methods: We performed a cross-sectional study in order to evaluate serum IGF-I in 97 age-matched healthy term infants: 50 FF and 47 BF. Results: FF infants showed higher values of IGF-I (38.9 ± 12 ng/ml) when compared to BF infants (26.7 ± 11.6 ng/ml; p < 0.05). A positive correlation was found between IGF-I values and Z score for weight (p < 0.001), BMI (p = 0.014), tricipital skin-fold thickness (p = 0.043) and age (p = 0.02). Conclusion: These results show that the IGF-I serum concentration is higher in FF infants. The observed association between IGF-I and Z score for weight, BMI, tricipital skin-fold thickness confirms the effect of different infant feeding on body size.