Fetal and maternal catecholamines in cesarean section.

The maternal and fetal sympathoadrenal system was studied by radioenzymatic measurement of the release of NA and A in 20 women with full-term uncomplicated pregnancies at cesarean section. Atropinization was performed 30 min or immediately before the induction of anesthesia. Before induction the mean level of maternal plasma NA in the i.v. atropinization group was 1.9 +/- 0.3 pmol/ml and in the i.m. group, 1.2 +/- 0.2 pmol/ml (mean +/- SE) (p greater than 0.05), and the levels of plasma A were 0.5 +/- 0.2 and 0.2 +/- 0.1 pmol/ml, respectively (p greater than 0.05). No significant rise was observed to be connected with the induction of anesthesia. Fetal umbilical arterial NA and A concentrations were higher than maternal values. CA concentration measured in the umbilical artery was 3-6 times higher than the corresponding values measured in the umbilical vein, indicating metabolization of CA in the placenta. Individual variation of fetal NA and A was very high, suggesting great individual alterations in the activity of the fetal sympathoadrenal system.