[Role of fetal catecholamines before and during birth]

It is true that developing fetus in uterus may be mostly influenced by maternal conditions. However, there is little evidence to prove the existence of nervous connection between fetus and mother. The biochemical and physiological phenomena of fetus in utero may be controlled mainly by fetal autonomy with nutritional supply from mother. The sympathoadrenal system of fetus has received much attention with the technical progress of catecholamine assays. Fetal plasma catecholamine concentrations during birth are remarkably higher than those in adult life. The function of those high catecholamine concentrations has been shown to control fetal circulation during hypoxia, to maintain glucose supply to the heart and brain, and to prepare the lung for ventilation. So it may be said that fetal plasma catecholamine surge at birth is essential to neonatal adaptation. Amniotic fluid catecholamines and their metabolites were higher in intrauterine growth retarded fetus, which consumed own catecholamine reserve in adrenal medulla before parturition. It is possible to estimate the fetal condition by measuring the concentration of catecholamines and their metabolites in amniotic fluid. The amniotic norepinephrine, epinephrine and particularly dopamine concentration has been found to increase toward term. The rise in dopamine has been assumed to stimulate intrauterine synthesis of prostaglandins. We demonstrated that L-dopa was metabolized to dopamine in fetal kidney and that dopamine in amniotic fluid was originated from fetal urine.