title: Leptin concentration in newborns' cord blood: relationship to gender and growth-regulating hormones.
abstract: OBJECTIVE
  To verify if plasma leptin concentrations of newborns at birth differ significantly between sexes; and to investigate the potential interactions between plasma leptin and growth-regulating hormones at birth.
  
  
  METHODS
  98 healthy newborns (48 male, 50 female) were studied. Leptin, insulin, cortisol, insulin-like growth factor-1 (IGF-1), testosterone, and sex hormone binding globulin (SHBG) concentrations were measured from venous blood collected from the umbilical cord vein immediately after birth.
  
  
  RESULTS
  The serum leptin concentration of newborns averaged 8.05(0.5) ng/ml. Females had significantly (P<0.005) higher serum leptin values than males [9. 6(0.8) vs 6.0(0.6) ng/ml]. IGF-1 was significantly (P<0.05) higher in females than in males [87(4) vs 74(5) microg/l], whereas SHBG was slightly lower [29(1) vs 33(2) nmol/l]. Insulin, cortisol, and testosterone serum concentrations were not statistically different between the sexes. Among the variables examined, birth weight (expressed as Z-score of weight) and insulin showed the highest degree of relationship with serum leptin in newborns (r=0.48 and r=0.31 respectively, P<0.001). Multiple regression analysis showed that Z-score of birth weight, gender and cortisol were able to account for approximately 44% of inter-individual variability of serum leptin concentrations in newborns.
  
  
  CONCLUSIONS
  Female newborns have significantly higher serum leptin concentrations than males. Insulin, IGF-1, testosterone, and SHBG did not independently affect leptin inter-individual variability when gender, Z-score of body weight, and cortisol were taken into account. Other factors may be involved in the differences in circulating leptin concentrations between the sexes in newborns.
authors.affiliation: Department of Pediatrics, University of Verona, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Maffeis
authors.forename: P
authors.initials: P
authors.lastname: Moghetti
authors.forename: R
authors.initials: R
authors.lastname: Vettor
authors.forename: A M
authors.initials: AM
authors.lastname: Lombardi
authors.forename: S
authors.initials: S
authors.lastname: Vecchini
authors.forename: L
authors.initials: L
authors.lastname: Tatò
mesh_terms: D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007231:Infant, Newborn; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D020738:Leptin / Q000032:analysis*; D008297:Male; D012016:Reference Values; D012044:Regression Analysis; D012727:Sex Characteristics; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood
chemical_list: D007328:Insulin; D020738:Leptin; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D007334:Insulin-Like Growth Factor I; D006854:Hydrocortisone