Leptina como marcadora do dimorfismo sexual em recém-nascidos

Abstract

Objective: To determine cord blood leptin levels in newborns appropriate for gestational age, according to gender, birth weight, birth height and ponderal index.Methods: A cross-sectional study was carried out with 132 term newborns appropriate for gestational age (68 females, 64 males), gestational age between 35-42 weeks. Data were collected through interviews with the mothers at the maternity, anthropometrycal study of the newborns, and cord blood estradiol, testosterone and leptin assays obtained immediately after birth.Results: The levels of leptin were significantly higher in females than in males (8.34±0.65 ng/ml versus 6.06±0.71 ng/ml; p = 0.000). The concentrations of estradiol and testosterone did not differ between males and females. Leptin levels were positively correlated with gestational age (r = 0.394, p < 0.01), birth weight (r = 0.466, p < 0.01), birth length (r = 0.335, p < 0.01) and ponderal index (r = 0.326, p < 0.01).Conclusions: Leptin concentration in the umbilical cord is positively correlated with gestational age, birth weight, birth height, and ponderal index, suggesting its participation in the neonatal growth process. In addition, a gender difference with higher levels of leptin in females neonates was observed, suggesting that the sexual dimorphism in relation to body composition already exists in newborns.

Does maternal smoking influence leptin levels in term, appropriate-for-gestational-age newborns?

“…Recent reports correlate leptin with neonatal growth 2,3 , and we previously reported that umbilical cord blood leptin levels were correlated to neonatal growth parameters 4 . However, contradictory results have been related regarding the effect of cigarette smoking on plasma leptin concentration 5,6 .…”

“…Previous reports 4,9 have also described these sex differences but their biological significance remains unknown. Saad and colleagues 10 suggested that these gender differences in leptin concentrations could reflect a sexbased difference in the regulation of leptin production by fetal adipose tissue.…”