Adiponectin in human cord blood: relation to fetal birth weight and gender.

Adiponectin is an adipocyte-derived plasma protein with insulin-sensitizing and antiatherosclerotic properties. The aim of this study was to examine whether adiponectin is present in human fetal blood, to define its association with fetal birth weight, and to evaluate whether dynamic changes in adiponectin levels occur during the early neonatal period. Cord blood adiponectin levels were extremely high (71.0 +/- 21.0 microg/ml; n = 51) compared with serum levels in children and adults and positively correlated with fetal birth weights (r = 0.4; P < 0.01). No significant differences in adiponectin levels were found between female and male neonates. In addition, there was no correlation between cord adiponectin levels and maternal body mass index, cord leptin, or insulin levels. Cord adiponectin levels were significantly higher compared with maternal levels at birth (61.1 +/- 19.0 vs. 17.6 +/- 4.9 microg/ml; P < 0.001; n = 17), and no correlation was found between cord and maternal adiponectin levels. There were no significant differences between adiponectin levels at birth and 4 d postpartum (61.1 +/- 19.0 vs. 63.8 +/- 22.0 microg/ml; n = 17). These findings indicate that adiponectin in cord blood is derived from fetal and not from placental or maternal tissues. The high adiponectin levels in newborns compared with adults may be due to lack of negative feedback on adiponectin production resulting from lack of adipocyte hypertrophy, low percentage of body fat, or a different distribution of fat depots in the newborns.