Elevated umbilical cord ghrelin concentrations in small for gestational age neonates

Ghrelin has orexigenic effects. It is present in umbilical cord plasma in full-term neonates, raising the prospect that ghrelin plays a role in fetal and neonatal energy balance. We measured ghrelin in small (SGA), appropriate (AGA), and large (LGA) for gestational age neonates and evaluated whether ghrelin levels are modulated by neonatal insulin and glucose concentrations. Plasma concentrations of ghrelin, insulin, and glucose were measured in cord blood sampled at birth in 123 SGA, AGA, and LGA neonates (gestational age, 24-41 wk) born to mothers with and without diabetes. Ghrelin was detected in samples from all infants. Its concentration was 40% higher in SGA neonates (mean +/- SD, 2436 +/- 657 pg/ml) compared with AGA (1738 +/- 380) and LGA (1723 +/- 269) neonates. There was a positive correlation between ghrelin and gestational age in AGA/LGA (r = 0.23; P < 0.05) and a negative correlation in SGA (r = -0.67; P < 0.005) neonates. Therefore, the difference in ghrelin between SGA and AGA/LGA neonates decreases with advancing gestational age. Birth weight z-score, maternal hypertension, and glucose concentrations were significant determinants of ghrelin concentrations. In conclusion, SGA neonates present with higher umbilical cord ghrelin plasma concentrations than AGA/LGA neonates. Ghrelin may play a physiological role in fetal adaptation to intrauterine malnutrition.