Being small for gestational age (SGA) is a risk factor of short stature in children. Genetic background such as mid-parental height (MPH) is known to influence growth of children born SGA. We studied the relationship between growth of children born SGA and MPH and studied the effects of insulin-like growth factor (IGF-I) and insulin-like growth factor binding protein 3 (IGFBP-3) on postnatal growth in children born SGA according to MPH.

Forty-nine neonates born SGA were included in this study. We defined corrected height standard deviation score (cHtSDS) by modified height SDS (HtSDS) based on their MPH. We categorized subjects into group 1 consisting of children with cHtSDS ≥0 (n=35) and group 2 consisting of children with cHtSDS <0 (n=14), and compared IGF-I and IGFBP-3 between the two groups.

The HtSDSs and cHtSDSs in groups 1 and 2 were 0.06±1.05 vs. -0.95±0.85 ( P =0.000) and 0.78±0.93 vs. -0.46±0.67 ( P =0.000), respectively. IGF-I SDS was higher in group 1 than in group 2 (2.82±3.69 vs. 0.23±2.42, P =0.012). Total cHtSDS (0.42±1.03) was significantly higher than HtSDS (-0.22±1.10) ( P =0.000).

Our results show that cHtSDS differs significantly from HtSDS. Growth assessment by standardized growth curve does not uniformly show effects of genetic factors. A more accurate assessment of growth uses a personalized corrected growth curve that considers the genetic factor measured by MPH.