Amniotic fluid norepinephrine concentration as an indicator of fetal sympathetic nervous activity. Effect of pregnancy complications.

The concentrations of norepinephrine in amniotic fluid and maternal plasma were measured in 71 third trimester pregnancies, 31 of which were uncomplicated and 40 complicated. The amniotic fluid norepinephrine concentration (mean +/- SD) in cases of hypertension treated with clonidine (0.4 +/- 0.1 ng/ml, n = 12) and in insulin-dependent diabetes (0.5 +/- 0.2 ng/ml, n = 7) was lower, and in renal insufficiency (1.7 +/- 0.8 ng/ml, n = 8) higher than in control subjects (0.7 +/- 0.4 ng/ml, n = 31). In fetal-growth retardation (0.6 +/- 0.2 ng/ml, n = 8) and in latent diabetes (0.7 +/- 0.2 ng/ml, n = 5) the values were similar to those in the control subjects. There was a significant positive correlation between mature lecithin-sphingomyelin (L/S) ratio and norepinephrine concentration. Clonidine-treated hypertension was associated with decreased (0.2 +/- 0.1 ng/ml) and renal insufficiency with increased (0.9 +/- 0.7 ng/ml) maternal plasma norepinephrine concentrations (control group, 0.3 +/- 0.1 ng/ml). The present results indicate that measurement of catecholamines in amniotic fluid can be useful in the evaluation of fetal sympathoadrenal function.