First Year Metabolic and Hormonal Behavior Define two Different Populations of SGA Newborn for Weight or Height

Context: Small-for-gestational-age (SGA) children have a particular metabolic and hormonal pattern at birth that changes rapidly.Objective: To evaluate the linear and weight growth in the first year of life in SGA children.Design: Prospective, monocentric cohort study.Setting: Real-world data collected from April 2012 to January 2016.Patients: SGA newborns uniformly defined by either growth or length lower than -2 SDs for gestational age.Interventions: All children were evaluated for 1 year after birth, at 3 days of life, then 3, 6, and 12 months after birth.Main outcome measures: Anthropometric parameters and biochemical variables, such as blood glucose, insulin, leptin, IGF-1, IGF binding protein-3 (IGFBP-3), and homeostasis model assessment - insulin resistance (HOMA-IR) index.Results: A total of 133 SGA children were enrolled. Length significantly improved 1 month after birth, whereas weight significantly increased only at 3 months after birth. Biochemical variables increased during the first year of life, showing a prediction by IGFBP-3 and HOMA-IR index. Then, the variables were divided considering either weight, length, or both, showing a different incidence. The biochemical variable changes recorded in the first step were maintained considering SGA children for weight or length, whereas they disappeared when weight and length were considered together.Conclusions: Our study shows a specific catchup growth for weight and length in SGA children. Moreover, we highlight that weight and length should be considered as independent parameters in SGA children, defining 2 different metabolic-hormonal populations with different conceivable predictive role in early catchup growth and in later growth and metabolic status.