Brain natriuretic peptide levels in the umbilical venous plasma are elevated in fetal distress.

We measured, by a specific radioimmunoassay, brain-natriuretic-peptide-like immunoreactive (BNP-LI) levels in the umbilical venous and arterial plasma of normal and distressed newborns. The indicated BNP-LI level in umbilical arterial plasma of normal newborns (3.5 +/- 0.9 fmol/ml, mean +/- SEM, n = 10) was significantly higher than that in umbilical venous plasma of the same newborns (2.2 +/- 0.5 fmol/ml). In the distressed newborns at term, the indicated BNP-LI level in umbilical venous plasma was 62.2 +/- 25.7 fmol/ml (n = 4), which was 19-fold higher than that of elective cesarean section cases (3.2 +/- 0.3 fmol/ml, n = 6; p < 0.05). The findings demonstrated that BNP was present in the human fetal circulation and that the plasma BNP level was elevated under fetal distress conditions.