Leptin Concentrations in Maternal and Umbilical Cord Blood in Relation to Maternal Weight, Birth Weight and Weight of the Placenta

Maternal serum and cord blood leptin concentrations at delivery

Introduction

Studies have demonstrated leptin involvement in the physiology and pathophysiology of pregnancy and suggest that leptin may be a prognostic marker for some complications of pregnancy although the association remains unclear. To date no studies have reported leptin reference intervals established in normal pregnancy, which could be used for interpreting the differences in leptin levels found in normal and pathological pregnancies.

Objective

To determine leptin concentrations at delivery, in maternal serum in normal pregnancy and in cord blood and to establish reference intervals for leptin.

Material and methods

The study was performed in 194 pregnant women without any comorbid health conditions. Leptin concentrations in maternal serum and in cord blood were measured by ELISA and subsequently analyzed by gestational age (weeks), maternal Body Mass Index (BMI), mode of delivery and infant gender and birth weight. For comparative analyses of normally distributed variables, parametric tests such as the Student–t were used to test the assumption of homogeneity or non-homogeneity of variance and a One-Way ANOVA when more than two groups were compared. The Pearson correlation coefficient was calculated to assess the correlation between normally distributed variables (p<0.05). The reference intervals for leptin were obtained by referring to the central 95% of laboratory test values.

Results

In normal pregnant women, the mean serum leptin concentration at delivery was 37.17 ± 28.07 ng/mL and the established reference interval was 33.19–41.14 ng/mL. The mean leptin concentration in cord blood was 14.78 ± 15.97 ng/mL and the established reference interval was 12.32–17.67 ng/mL. There was a statistically significant positive correlation between maternal serum and cord blood leptin concentrations (r = 0.37; p = 0.00). Mean leptin concentrations in cord blood increased with gestational age (p = 0.00). No statistically significant differences in maternal serum and cord blood leptin concentrations were found in regard to mode of delivery and neonatal gender. A statistically significant correlation was found between maternal serum leptin and third-trimester BMI (r = 0.22; p = 0.00), but there was no association between maternal BMI and cord blood leptin concentration. There was a statistically significant positive correlation between cord blood leptin concentration and birth weight (r = 0.23; p = 0.00).

Conclusions

Reference intervals for leptin in maternal serum and in cord blood established in normal pregnancy could be used in clinical practice for interpreting the differences in leptin concentrations found in normal pregnancy and in complications of pregnancy. The results indicate a strong association between maternal serum leptin levels and obesity and between cord blood leptin levels and birth weight.

Association of cord blood ghrelin, leptin and insulin concentrations in term newborns with anthropometric parameters at birth

BACKGROUND

Ghrelin, leptin and insulin, generally considered as regulators of energy homeostasis of the organism may be related to fetal and early postnatal growth. Numerous studies have confirmed the presence of these hormones in the cells of the fetus indicating their importance in development at early stages of life.

METHODS

This study analyzed active and total ghrelin by radioimmunoassay (RIA), leptin and insulin concentrations by enzyme-linked immunosorbent assay (ELISA) in 65 cord blood samples, from term newborns, and measured the birth anthropometric parameters [birth weight (BW), head circumference, chest, stomach, thigh and arm circumference].

RESULTS

Active ghrelin (AG) concentrations correlated negatively with BW, head circumference, stomach and thigh circumference. When divided by gender, AG correlated negatively with males' BW, stomach and thigh circumference. Females' head circumference correlated negatively with AG. Cord leptin correlated positively with arm circumference. When divided by gender, cord leptin was positively associated with BW and stomach circumference in male newborns and with thigh and arm circumference in female newborns. Insulin concentrations tended to correlate positively with BW in male newborns.

CONCLUSIONS

In summary, it was confirmed that cord blood ghrelin, leptin and insulin correlate with anthropometric parameters at birth. This study showed a negative correlation of AG with anthropometric parameters, which may emphasize that this hormone is an indicator of growth restriction. This is in contrast to cord leptin and insulin, which are more connected with overgrowth. Taking all the results into consideration, the metabolic status of the fetus and newborn is an essential component in understanding the regulation of perinatal development.