Serum Leptin Concentrations During the Perinatal Period

We aimed to study maternal and infant serum leptin concentrations during the perinatal period and their relationship to the body weight of mothers and newborns. Serum leptin values were measured by enzyme-linked immunoadsorbent assay (ELISA) (R&D systems) in 26 healthy, term neonates during the first (N1) and fifth (N5) day after birth and were compared with serum leptin values in maternal blood (MS), amniotic fluid (AF), and umbilical cord (UC) at delivery. Twenty-five healthy, nonpregnant women, age and body weight-matched to the mothers, were used as controls (C). Infant serum leptin concentrations declined significantly after birth from UC to the N5 samples (p<0.003). MS leptin values were significantly higher than UC, N1, N5, and C values (p<0.001), while AF values were significantly lower than in controls (p<0.001). UC, but not MS leptin values correlated significantly with the birth weight of infants (r = 0.6; p<0.03). The elevated values of leptin in maternal serum and the regressing pattern of infant leptin values after birth suggest an additional, probably placental source of this protein during pregnancy, possibly contributing to the regulation of fetal body weight.