Influence of gestational age and intrauterine growth on leptin concentrations in venous cord blood of human newborns.
BACKGROUND
The ob gene product leptin is involved in the regulation of body weight and energy expenditure, suggesting a potential role of leptin in embryonal and fetal development and progression of pregnancy. In term infants, leptin concentrations showed a positive correlation with birth weight. We aimed at comparing leptin cord blood levels in AGA (appropriate for gestational age) to SGA (small for gestational age) preterm and term newborns.


METHODS
Ninety-seven human newborns, 47 females and 50 males, 33 born at term and 64 born before 36 weeks of gestation, were studied prospectively. Leptin concentrations in venous cord blood were determined using a specific RIA (radioimmunoassay).


RESULTS
In term newborns, mean gestational age (GA) was 39 weeks (wk) (+/- 0.7 wk) and mean birth weight (BW) was 3316 g (+/- 473 g); in preterm newborns (n = 64), mean GA was 30 wk (+/- 5.0 wk) and mean BW was 1398 g (+/- 505 g). Mean standard deviation score of birth weight (BW SDS) was calculated as - 0.47. Mean leptin concentrations in term newborns differed significantly from those in preterm newborns (9.21 +/- 2.63 ng/ml vs. 1.58 +/- 0.88 ng/ml; p < 0.0001). In preterm and term infants, leptin concentrations showed a linear correlation with BW (r = 0.46; p < 0.0001) and GA (r = 0.48; p < 0.0001), respectively. Leptin levels were best predicted by an exponential regression model with GA (Leptin = exp(- 4.41 + 0.14 x GA); r = 0.61; p < 0.0001). Using multivariate regression analysis (r = 0.57; p < 0.0001), we found significant influences of GA (p < 0.00001) and BW SDS (p < 0.05) on leptin levels. No difference was observed between leptin values in AGA versus SGA preterm infants.


CONCLUSIONS
These data suggest fetal leptin levels to be primarily determined by GA and additionally modulated by growth restriction in term newborns. We found a dramatic increase at weeks 33 to 35 of gestation and no modulation by BW SDS in very preterm infants.
Stoll-Becker
S
S
Department of Pediatrics, University Giessen, Germany. simone.stoll-becker@paediat.med.uni-giessen.de
Kreuder
J
J
Reiss
I
I
Etspüler
J
J
Blum
W F
WF
Gortner
L
L
D001724:Birth Weight; D005314:Embryonic and Fetal Development; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D007236:Infant, Small for Gestational Age / Q000097:blood*; D020738:Leptin / Q000097:blood*; D008297:Male; D015999:Multivariate Analysis; D011247:Pregnancy; D011446:Prospective Studies; D011863:Radioimmunoassay; D012044:Regression Analysis
D020738:Leptin