Leptin levels in maternal and cord serum: relationship with fetal development and placental weight.

Abstract

To test the hypothesis that the circulating levels of leptin in the maternal and cord serum correlate with the birthweight of the newborns and with the weight of the placenta. In a population of 85 women from northern Greece who gave birth to an equal number of full-term infants, we calculated the concentration of leptin in the maternal serum as well as in the cord serum, right after delivery, by using an immunoradiometric assay. The correlation between these values, the maternal BMI before pregnancy and at the time of delivery, the neonatal BMI, Ponderal Index, and the placental weight was studied. Mean maternal leptin showed a statistically significant difference from mean cord serum leptin (14.7 and 7.07 ng/ml, respectively) and was positively correlated to the maternal BMI at the time of delivery (r = 0.3, P = 0.016), but not to neonatal BMI. A positive correlation between the mean cord serum leptin and the BMI of the neonates (r = 0.26, P = 0.031 ) was found. There was no correlation between the maternal BMI at the time of delivery and the neonatal BMI. Similarly, no correlation could be established between the placental weight and the levels of leptin in the maternal or in the cord serum but a positive correlation between placental weight, neonatal BMI and weight, and mothers' BMI was observed. Finally, although a noteworthy difference between the mean leptin levels of neonates of two different sexes was observed (male 5.9 ng/ml, female 7.8 ng/ml), that difference never reached a statistically significant level. The maternal leptin level could not be used as a reliable marker of fetal growth but a positive correlation between cord serum leptin and fetus growth is suggested.