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 pep tide system in hypertensive pregnancies with and without signs of increased fetal systemic venous pressure and in pregnancies complicated by fetal aci demia during labor. Methods: Umbilical artery plasma N-terminal peptide of proatrial natriureti c peptide concentrations were measured in neonates by radioimmunoassay. The control group consisted of 50 neonates with uncomplicated gestation and la bor. In group 1, there were 22 newborns of hypertensive pregnancies. Dopple r 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 complicat ed by maternal hypertensive disorder. Atrial pulsations in the umbilical ve in and retrograde diastolic blood velocity pattern in the umbilical artery were detected in every case. Group 3 was composed of 27 newborns of uncompl icated 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 I, neonates with abnormal umbilical artery blood velocity pattern had highe r N-terminal peptide of proatrial natriuretic peptide concentrations than n eonates with normal umbilical artery Doppler findings (P < .006). N-termina l peptide of proatrial natriuretic peptide concentrations were higher in gr oup 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 i n fetuses with severe placental insufficiency and signs of congestive heart failure. (Obstet Gynecol 2001;97:23-8. (C) 2001 by The American College of Obstetricians and Gynecologists.)