C. Maffeis et al., Leptin concentration in newborns' cord blood: relationship to gender and growth-regulating hormones, INT J OBES, 23(9), 1999, pp. 943-947
AIMS: 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.
SUBJECTS: 98 healthy newborns (48 male, 50 female) were studied, Leptin, in
sulin, cortisol, insulin-like growth factor-1 (IGF-1), testosterone, and se
x 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/m
l. Females had significantly (P < 0.005) higher serum leptin values than ma
les [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) mu g/l], whereas SHBG was slightl
y lower [29(1) vs 33(2) nmol/l]. Insulin, cortisol, and testosterone serum
concentrations were not statistically different between the sexes. Among th
e variables examined, birth weight (expressed as Z-score of weight) and ins
ulin showed the highest degree of relationship with serum leptin in newborn
s (r = 0.48 and r = 0.31 respectively, P < 0.001). Multiple regression anal
ysis showed that Z-score of birth weight, gender and cortisol were able to
account for approximate to 44% of inter-individual variability of serum lep
tin concentrations in newborns.
CONCLUSIONS: Female newborns have significantly higher serum leptin concent
rations than males. Insulin, IGF-1, testosterone, and SHBG did not independ
ently affect leptin inter-individual variability when gender, Z-score of bo
dy weight, and cortisol were taken into account, Other factors may be invol
ved in the differences in circulating leptin concentrations between the sex
es in newborns.