LEPTIN CONCENTRATION IN CORD-BLOOD CORRELATES WITH INTRAUTERINE GROWTH

Leptin is an adipocyte-derived peptide hormone regulating energy balan ce in experimental animals. Although the physiological function of lep tin in humans is still unclear, its secretion is closely related to fa t mass in adult humans. To examine how fetal growth correlates with le ptin levels at birth, an umbilical cord venous blood sample was obtain ed at the delivery from 50 term newborn infants. Twenty-eight of the n ewborn infants had birth weights appropriate for gestational age (AGA; mean +/- SEM, 3362 +/- 90 g; relative birth weight, -0.08 +/- 0.2 SD) , 9 were large for gestational age (birth weight, 4655 +/- 165 g; rela tive birth weight, 3.2 +/- 0.3 SD; P < 0.001 vs. AGA newborn infants), and 13 were small for gestational age (SGA; birth weight, 2385 +/- 69 g; relative birth weight, -2.2 +/- 0.08 SD; P < 0.001 vs. AGA newborn infants). Leptin concentrations were higher in large for gestational age (35.7 +/- 8.0 mu g/L; P < 0.005), but lower in SGA (3.3 +/- 0.5 mu g/L; P < 0.001) than in AGA infants (14.5 +/- 2.8 mu g/L). When adjus ted for differences in body weight, mean leptin levels mere similar in the three newborn groups. Leptin concentration correlated closely wit h both absolute and relative birth weights (r = 0.71; P < 0.001 in bot h), with cord blood insulin concentration (r = 0.67; P < 0.001), and w ith placental weight (r = 0.60; P < 0.001). These data suggest that le ptin is synthesized in utero, and that the circulating leptin concentr ation relates to the intrauterine growth pattern.