[Leptin as a marker of sexual dimorphism in newborn infants].
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.
Pardo
Inês M G C
IM
Universidade Estadual de Campinas (UNICAMP), Campinas, SP. doctorpardo@hotmail.com
Geloneze
Bruno
B
Tambascia
Marcos A
MA
Pereira
José L
JL
Barros Filho
Antonio A
AA
D015415:Biomarkers / Q000097:blood; D001724:Birth Weight; D001827:Body Height; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D005260:Female; D005312:Fetal Blood; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D020738:Leptin / Q000097:blood*; D008297:Male; D012727:Sex Characteristics; D012737:Sex Factors; D013739:Testosterone / Q000097:blood
D015415:Biomarkers; D020738:Leptin; D013739:Testosterone; D004958:Estradiol