Correlation of elevated leptin levels in amniotic fluid and maternal serum in neural tube defects

To measure maternal serum and amniotic fluid leptin concentrations in pregnant women diagnosed antenatally as having fetuses with a neural tube defect in the second trimester.

Twenty pregnant women who had fetuses with a neural tube defect detected on ultrasonography (neural tube defect group) in the second trimester and 20 women who had abnormal triple screens indicating an increased risk for Down syndrome but had healthy fetuses (control group) were enrolled in the study. Amniotic fluid was obtained by amniocentesis, and maternal serum samples were taken simultaneously.

The mean leptin levels in amniotic fluid (P <.001) and maternal serum (P <.05) of patients who had fetuses with a neural tube defect were found to be significantly higher than control group levels. The mean leptin levels in maternal serum of both groups were also higher than leptin levels in amniotic fluid (P <.05 for the neural tube defect group and P <.001 for the control group). Although there were significant correlations between maternal weight, weight gain, body mass index at the time of amniocentesis, and maternal serum leptin concentrations in both groups, a significant correlation between leptin concentrations in maternal serum and amniotic fluid was found only in the neural tube defect group (P <.05).

We found significantly higher leptin levels in both amniotic fluid and maternal serum of patients who had fetuses with a neural tube defect. We suggest that the main source of leptin in amniotic fluid of pregnant women who had fetuses with a neural tube defect is the leakage into amniotic fluid from cerebrospinal fluid. The increase of maternal serum leptin concentrations has been attributed to the transportation of amniotic fluid leptin to the maternal circulation.