NEONATAL CORD-BLOOD LEPTIN - ITS RELATIONSHIP TO BIRTH-WEIGHT, BODY-MASS INDEX, MATERNAL DIABETES, AND STEROIDS

Leptin is a 16-kD protein encoded by the ob/ob (obesity) gene. In rode nts it plays a role in obesity, diabetes, fertility, and neuroendocrin e function, In humans serum concentrations of leptin correlate with to tal body fat in both adults and children. We measured cord blood lepti n in 186 neonates that included 82 appropriate for gestational age (AG A), 47 large for gestational age (LGA), 20 infants of diabetic mothers , 52 preterm infants, and 15 intrauterine growth-retarded (IUGR) infan ts. There were 16 pairs of twins. The mothers of 17 preterm infants we re treated with steroids before delivery. Leptin (mean +/- SD) concent ration in term, AGA infants (39.4 +/- 1.1 wk) with birth weight (BW) o f 3.2 +/- 0.3 kg, body mass index (BMI) of 12.6 +/- 1.1 was 4.01 +/- 3 .5 ng/mL. BW correlated with cord leptin (p, = 0.002) in a multivariat e analysis controlling for potential confounders. Both LGA infants and infants of diabetic mothers had higher cord leptin concentration 7.3 +/- 3.8 and 6.1 +/- 4.8 ng/mL, respectively, compared with AGA infants (p < 0.05). Preterm infants had a mean leptin level of 1.8 +/- 0.97 n g/mL and a 3-fold elevation was seen if mothers received steroids ante natally (p = 0.006). IUGR infants had increased leptin (6.5 +/- 3.9 ng /mL, p = 0.03). Concerning the twin pairs, the smaller had a higher le ptin level compared with larger twin (4.1 +/- 9.51 versus 2.8 +/- 5.14 , p = NS). Neonatal cord leptin concentrations correlate well with BW and BMI. No gender differences were found in cord blood leptin. Matern al obesity had no effect on cord leptin, whereas exogenous maternal st eroids increased neonatal leptin concentrations.