Objectives: To investigate the association of ghrelin, leptin, and insulin levels in the umbilical cord blood of the preterm and term infants with anthropometric measurements and glucose metabolism. Methods: Sixty-nine infants who were born between November 2004 and June 2005 were included in the study. Pregnancy ages, birth weights, heights, head circumferences, and Ponderal Indexes (PI) were identified. Ghrelin, leptin, insulin, and glucose levels in the umbilical cord blood were studied. Results: Eighteen infants out of 69 infants were preterm (34.6 +/- 0.43 weeks), and 33 infants were term (38.7 +/- 0.14 weeks). All preterm infant weights were appropriate for gestational age (AGA); 33 of the term infants' weights were AGA and 18 were large for gestational age (LGA). Leptin, insulin, and glucose levels of term infants were significantly higher compared with the preterm infants (p < .0001, p < .001, and p < .0001, respectively); no significant difference was detected in the ghrelin levels between the two groups (p > .05). The leptin and insulin levels of the term LGA infants were higher compared with the term AGA and preterm AGA infants (p < .05, for all). No difference was detected between the three groups regarding serum ghrelin levels (p > .05). No difference was found in the glucose levels between term AGA and LGA infants (p > .05); however, the serum glucose levels of term AGA and LGA infants were higher compared with levels in preterm AGA infants (p < .05, for both). A positive correlation was demonstrated in all study groups between leptin and insulin with gestational age, body weight, height, head circumference, and PI. A positive correlation was found between serum leptin levels with gestational age and insulin levels in preterm infants, and between serum leptin levels and insulin and glucose levels in term infants. No association was found between ghrelin and anthropometric measurements, leptin, insulin, and glucose levels (p > .05, for all). Conclusions: The increase of leptin production with increased gestational age, and the strong association with anthropometric measurements supports the opinion that leptin behaves as a fetal growth factor. Leptin in intrauterine life is in close association with insulin and glucose metabolism. Although ghrelin was at measurable levels in preterms, no association with fetal growth and glucose metabolism could be demonstrated in preterm and term infants.