ABSTRACT
Leptin plays an important role in regulating body composition through modulation of
appetite and energy expenditure. We hypothesized that leptin levels in umbilical cord
blood correlate with newborn body weight and habitus. We also hypothesized that infants
of diabetic mothers would demonstrate altered leptin metabolism. Venous blood was
sampled at birth from the umbilical cords of 105 infants (74 infants of nondiabetic
mothers, and 31 infants of diabetic mothers). Thirty-nine mothers had plasma leptin
concentrations measured. Analysis was done using Student's t-test, Pearson's correlation, and Spearman's correlation. Univariate/multivariate
regression was used for analysis of factors associated with leptin concentration in
umbilical cord plasma. Maternal and newborn characteristics were correlated with log
leptin levels in umbilical venous plasma. Leptin concentration in umbilical cord plasma
correlated best with birth weight for newborns of both nondiabetic and diabetic mothers
(p < 0.01 for either). Umbilical cord plasma concentration of leptin was higher in infants
of diabetic mothers than in infants of nondiabetic mothers (2.53 ± 1.09 vs. 1.76 ±
0.82; p < 0.001). Multiple regression analysis revealed a significant (p < 0.01) relationship between umbilical cord leptin level and newborn birth weight,
as well as maternal DM, but not with gestational age. Similarly, there was no significant
correlation with maternal plasma leptin concentration. The strong correlation of leptin
concentration in umbilical cord plasma with newborn birth weight, and the lack of
significant correlation with maternal leptin plasma levels, suggest that normal fetal
leptin metabolism reflects fetal size and/or body habitus independent of maternal
leptin metabolism. On the other hand, the higher umbilical plasma levels in infants
of diabetic mothers may reflect an influence of altered fetal insulin homeostasis
on fetal leptin metabolism, and suggests that maternal diabetes may influence fetal
leptin metabolism.
Keywords
Leptin - diabetes - birth weight
