Catecholamines in amniotic fluid as indicators of intrapartum fetal stress

Catecholamines were measured in the amniotic fluid and in the first voided newborn urine obtained from appropriate-for-date infants of term deliveries. Catecholamine values in the amniotic fluid and urine were nearly equal when expressed in terms of creatinine. Significant positive correlations were observed between the amniotic fluid and urine of norepinephrine and epinephrine. In normal cases (n = 32) that underwent uneventful vaginal delivery, the 95% confidence limits for norepinephrine and epinephrine in the amniotic fluid were 1.53 to 2.33 ng/ml and 0.16 to 0.30 ng/ml, respectively. In cases of moderate stress (n = 12), only norepinephrine showed significantly higher values than the normal cases, while in cases of severe stress (n = 12), norepinephrine became more significantly high, and epinephrine was found to be elevated significantly. A significant difference was noted in the incidence of fetal stress between the infants with more than and those with less than 2.30 ng/ml of norepinephrine, the upper limits of the normal 95% confidence limits. However, for epinephrine such a significant difference was not noted. It was concluded that amniotic fluid catecholamines are of fetal origin and reflect fetal sympathoadrenal activity directly, even during labor, and that their level may be a good indicator of fetal condition and stress.