The relationship of the levels of leptin, insulin-like growth factor-I andinsulin in cord blood with birth size, ponderal index, and gender difference

In humans, serum levels of leptin correlate with total body fat in both adu lts and children. After collecting cord blood from 156 term neonates (82 ma les, 74 females; 132 AGA and 22 LGA), we measured the cord levels of leptin , insulin and IGF-I to determine the relationships between these three horm ones and relationships of these hormones with birth size (birth weight and ponderal index for adiposity in newborn) and gender. The leptin and IGF-I l evels were significantly higher in the LGA group (9.2+/-4.0 ng/ml and 96.1/-34.1 ng/ml, respectively) than in the AGA group (4.8+/-3.8 ng/ml and 56.4 +/-37.6 ng/ml, respectively). A significant positive correlation was observ ed between leptin levels and birth weight, and a weaker correlation between leptin levels and birth height. IGF-I level significantly correlated with birth weight and birth height, but there was no correlation between the lev els of insulin and birth weight. There was no relationship between the leve ls of IGF-I, insulin and leptin, Ponderal index was higher in LGA than in A GA, A significant correlation was also observed between the levels of lepti n and ponderal index, but not between the levels of insulin or IGF-I and po nderal index. The levels of leptin and ponderal index were higher in female s than males despite no gender differences in gestational age and birth wei ght. In conclusion, our results suggest that the level of IGF-I is a useful index for fetal growth during late gestation, and the development of adipo se tissue is the major determinant of fetal serum leptin levels, the produc tion of which is not regulated by insulin or IGF-P. Ik addition, a gender d ifference with a higher level of leptin in female neonates suggests that se xual dimorphism in adipose tissue already exists in utero.