GH-IGF-IGFBP Axis and Metabolic Profile in Short Children Born Small for Gestational Age

Small for gestational age (SGA) is defined as a birth weight and/or birth length below -2 standard deviation scores (SDS), adjusted for gestational age (Clayton et al., 2007). To determine whether a child is born SGA, accurate knowledge of gestational age, accurate measurements of weight and length at birth, and an appropriate reference population to calculate the standard deviation scores are required. The child can be further subclassified as SGA for weight, SGA for height or SGA for height and weight. SGA only refers to size at birth and does not take fetal growth into account. The term intrauterine growth retardation (IUGR) is used when the fetus suffers from reduced fetal growth, based on at least 2 subsequent ultrasound measurements. A child born SGA has not necessarily suffered from IUGR, whereas a child with IUGR late in gestation can have a normal size at birth. These different fetal growth patterns are shown in Figure 1.