Maternal smoking and elevation of catecholamines and metabolites in the amniotic fluid.

To assess the effect of maternal smoking on fetal adrenergic activity, simultaneous measurements in amniotic fluid of the parent catecholamines, dopamine (DA), norepinephrine (NE), and epinephrine (E), as well as the specific intraneuronal deaminated metabolites of DA, 3,4-dihydroxyphenylacetic acid (DOPAC), and of NE, 3,4-dihydroxyphenylglycol (DOPEG), were made by radioenzymatic assay. In the second trimester, a significant (p less than 0.002) and selective elevation of the mean DOPEG concentration was noted in the amniotic fluid of smokers (N = 8) as compared to nonsmokers (N = 36). In the third trimester, significant elevations were found in the mean amniotic fluid concentration of E (p less than 0.0002) and NE (p less than 0.0005), as well as DOPEG (p less than 0.0002), of smokers (n = 12) when compared to nonsmokers (N = 12). There were no significant differences in amniotic fluid concentrations of DA and its deaminated metabolite DOPAC. Since compartmentalization of catecholamines exist between the maternal and fetal circulations, the elevated levels of NE, E, and DOPEG in the amniotic fluid of smokers suggests fetal adrenergic activation as a result of fetal hypoxia and/or by a direct effect of nicotine on the fetal adrenergic system.