Perinatal determination of Leptin in mothers and neonates with diagnosis of retard of intra-uterine growth (RCIU) Recently it has been described that the leptin presents hormonal activity, acting on receivers and that it isinvolved in the regulation of the metabolic efficiency, spend energy and nutritious ingestion. Has been synthesizedin the sincitiotrofoblastos and it is secreted inside the maternal circulation. The leptin has also been related in thedeposit of fat. Since in the last trimester of the human pregnancy, in a characteristic way a relatively increaseddeposit of fat exists and that this leaves depletado evidently in the cases of RCIU, it is then probable that theleptin keeps relationship with the entity. The objective of this study was to investigate if differences exist among theleptinmensurations obtained in a group of healthy patients and with RCIU.The study was carried out in 12 patients with RCIU (cases) and 9 patients without RCIU (you control). For such a reason they took samples of maternal blood and blood cord and of amniotic liquid (THE). In the paired study (n=9) the leptin levels in children born with RCIU presented lower concentrations that the children control (p=0.05). The leptin concentrations in blood cord were correlated significantly with the weight of the neonate (p = 0.0002) and I weigh placentario (p = 0.048). It was not to significant correlation statistically of the leptin levels in maternal blood with the weight of the neonate and the placentario weight. The concentrations of amniotic liquid showed an inverse and statistically significant correlation with the weight neonatal (p = 0.035), but not with the placentario weight (p = 0.071). Inverse and statistically significant correlations were observed among: concentrations of maternal leptin and leptin in blood cord (p = 0.034); cord leptin with leptin in liquid amniotic (p = 0.011) and positive correlation between maternal leptin and leptin in the amniotic fluid (p = 0.01).