Ontogeny of serum leptin concentrations in the human

OBJECTIVE Serum leptin concentrations reflect the fat mass of an individual. Fetal growth is rapid and it might be expected that major changes in circulating leptin concentrations in the fetus and neonate take place. We have studied the ontogeny of serum leptin concentrations in cord blood samples obtained by cordocentesis between 14 end 32 weeks of gestation and in samples obtained at term. PATIENTS Cordocentesis samples from 10 appropriately grown for gestational age (AGA) and 10 intrauterine growth restricted (IUGR) fetuses. The results were compared with cord serum leptin concentrations obtained in 39 term healthy pregnancies. RESULTS In the AGA and term pregnancies serum leptin concentrations changed little up until 38 weeks of gestation when there was an increase in concentration (Pre 38 weeks 3.5 mu g/l (SEM 0.3); Post 38 weeks 5.6 mu g/l (SEM 0.7): Mann Whitney P = 0.03). Serum leptin concentrations were similar in the AGA and IUGR fetuses (AGA 5.9 mu g/l (SEM 3.0); IUGR 4.2 mu g/l (SEM 1.5): Mann-Whitney P = ns). Serum leptin was strongly related to birth weight (r = 0.58; P< 0.001) and birth length (r = 0.32; P = 0.05) in the term babies but not in the AGA or IUGR groups. CONCLUSION Serum leptin concentrations in the fetus appear to be independent of gestational age and only rise towards the end of gestation. This late change probably reflects the changes in the accretion of body fat. There appears to be little difference in serum leptin concentrations between AGA and IUGR fetuses.