Umbilical plasma concentration of endothelin-1 in intrapartum fetal stress: effect of fetal heart rate abnormalities.

OBJECTIVE

To measure the umbilical plasma concentration of endothelin (ET)-1 in the presence of labor, fetal heart rate (FHR) abnormalities, and fetal hypoxia.

METHODS

Umbilical and maternal plasma concentrations of ET-1 were measured in 100 pregnant women at full-term deliveries (60 with vaginal delivery without induction and 40 with elective cesarean delivery without labor). We assessed the FHR pattern, measured umbilical blood gases and plasma concentration of vasopressin, and investigated the relationships between the umbilical vein-artery ET-1 concentration difference and these variables.

RESULTS

The concentration of ET-1 in the umbilical vein was higher than in the umbilical artery and the maternal vein in all cases. The umbilical vein-artery ET-1 concentration difference (mean +/- standard error of the mean) was significantly greater in the vaginal delivery group (4.5 +/- 2.0 pmol/L) than in those delivered by elective cesarean (1.7 +/- 1.5 pmol/L) (P < .05). The umbilical vein-artery ET-1 concentration difference was significantly greater when more than three episodes of severe variable decelerations occurred during the 30-minute period before delivery (7.0 +/- 2.0 pmol/L) than in the absence of any decelerations (1.6 +/- 1.5 pmol/L) (P < .05). The umbilical vein-artery ET-1 concentration difference correlated positively with the umbilical arterial concentration of vasopressin (r = 0.45, P < .05) and negatively with the umbilical arterial oxygen pressure (r = -0.47, P < .05).

CONCLUSION

In cases of vaginal delivery with FHR abnormalities and with fetal hypoxia, the fetoplacental concentration of ET-1 was increased.