Leptin values in placental cord blood of human newborns with normal intrauterine growth after 30-42 weeks of gestation

Objective: To evaluate leptin values in placental cord blood of newborns wi th normal intrauterine growth after 30-42 weeks of gestation. Design: Lepti n, a protein encoded by the ob gene, plays an important role in the regulat ion of feeding behaviour and energy balance in rodents, primates and humans . The presence of leptin in human amniotic fluid and cord blood has recentl y been reported in human gestations at term and the possible role of leptin in human fetal growth suggested. However, little is known of leptin synthe sis during human foetal development. Thus, the aim of our work was to measu re leptin (RIA, Linco Research, Inc.) in placental cord blood of human newb orns at different fetal ages. Patients: One hundred and twenty-six healthy newborns with normal intra uteri ne growth were studied. Twenty-nine were p reterm (15 males and 14 females; gestational age: 30-36 weeks) and 99 were at term (49 males and 48 females; gestational age: 37-42 weeks). Results: L eptin values increase progressively throughout gestation from 1.30 +/- 0.53 ng/ml at 30 weeks of gestation to 7.98 +/- 4.96 ng/ mi (mean +/- SD) at te rm, and correlate positively with birth weight (r = 0.56, p < 0.005, n = 12 6), length (r = 0.37, p < 0.005, n = 126), BMI (r = 0.57, p < 0.005, n = 12 6), head circumference (r = 0.37, p < 0.005, n = 126), gestational age (r = 0.48, p < 0.005, n = 126) and placental weight (r = 0.38, p < 0.003, n = 5 9). Leptin values are statistically significantly lower (p < 0.005) preterm (median: 2.05 ng/ml; range: 0.7-8.3 ng/ml) than at term (median: 7.0 ng/ml ; range: 1.1-28.1 ng/ml). Leptin values are also significantly (p < 0.005) higher in females (median: 7.2 ng/ml; range: 0.9-23.6 ng/ml, n = 62) than i n males (median: 4.8 ng/ml; range: 0.7-28.1 ng/ml, n = 64), although there are no differences in weight (2,864 +/- 536 g in females vs. 2,937 +/- 744 g in males). Multiple regression analysis shows weight to be a positive sex -independent predictor of serum leptin values (p < 0.0005). Sex also proves to be a predictor of leptin, independently of weight and is higher in fema les than in males (p < 0.003). Conclusion: Leptin is present in placental h uman cord blood after 30-42 weeks of gestation. Newborn weight and sex are independent predictors of leptin values.