Umbilical artery N-terminal peptide of proatrial natriuretic peptide in hypertensive pregnancies and fetal acidemia during labor

Objective: To assess the activity of the human fetal atrial natriuretic peptide system in hypertensive pregnancies with and without signs of increased fetal systemic venous pressure and in pregnancies complicated by fetal acidemia during labor. Methods: Umbilical artery plasma N-terminal peptide of proatrial natriuretic peptide concentrations were measured in neonates by radioimmunoassay. The control group consisted of 50 neonates with uncomplicated gestation and labor. In group 1, there were 22 newborns of hypertensive pregnancies. Doppler ultrasonography showed abnormal umbilical artery blood velocity waveform in five cases and normal nonpulsatile umbilical vein blood velocity profile in every case. Group 2 consisted of five newborns of pregnancies complicated by maternal hypertensive disorder. Atrial pulsations in the umbilical vein and retrograde diastolic blood velocity pattern in the umbilical artery were detected in every case. Group 3 was composed of 27 newborns of uncomplicated pregnancies with fetal acidemia (pH 7.10 or less) during labor. Results: In groups 1-3, N-terminal peptide of proatrial natriuretic peptide concentrations were higher (P < .001) than in the control group. In group 1, neonates with abnormal umbilical artery blood velocity pattern had higher N-terminal peptide of proatrial natriuretic peptide concentrations than neonates with normal umbilical artery Doppler findings (P < .006). N-terminal peptide of proatrial natriuretic peptide concentrations were higher in group 2 (P < .002) than in groups 1 and 3. Conclusion: Maternal hypertensive disorder and fetal acidemia during labor stimulate fetal atrial natriuretic peptide production, which was greatest in fetuses with severe placental insufficiency and signs of congestive heart failure.