Influence of leptin and the TNF system on insulin resistance in pregnancy and their effect on anthropometric parameters of newborns.

Background: We studied the contribution of the tumor necrosis factor system and leptin to insulin resistance during the course of normal pregnancy.

Methods: Forty-five healthy pregnant women (15 in the 1st, 15 in the 2nd2 and 15 in the 3rd3 trimester) and 25 age-matched healthy nonpregnant women as controls. Twenty-three newborns delivered by women followed in the 2nd and 3rd trimesters were also investigated. Fasting serum immunoreactive tumor necrosis factor-alpha, soluble tumor necrosis factor receptor-1, soluble tumor necrosis factor receptor-2, leptin (by enzyme-linked immunoassay) and C-peptide (by radioimmunoassay) concentrations in the patients and controls were measured. Body weight, length and head circumference of the newborns were analyzed in connection with the measured maternal parameters.

Results: Significantly elevated tumor necrosis factor-alpha, tumor necrosis factor receptor-1 and -2, leptin, and C-peptide levels were found in the 3rd3 trimester as compared with the 1st1 and 2nd2 trimesters and with the nonpregnant controls. Tumor necrosis factor-alpha, tumor necrosis factor receptor-2, C-peptide, leptin concentrations and body mass index were found to be in a significant positive linear correlation with each other. Significant negative linear correlations were calculated among maternal serum C-peptide, tumor necrosis factor-alpha and leptin concentrations and the head circumference of the newborns.

Conclusions: In conclusion, increased tumor necrosis factor-alpha and leptin levels may contribute to insulin resistance in late pregnancy. Tumor necrosis factor-alpha and leptin may be regulators of intrauterine bone development of newborns.