Adrenomedullin is increased in the fetoplacental circulation in intrauterine growth restriction with abnormal umbilical artery waveforms

OBJECTIVE: To examine whether adrenomedullin, a novel vasoactive peptide pr oduced by the placenta, participates in the uteroplacental hemodynamic alte rations in intrauterine growth restriction. we studied the correlation betw een adrenomedullin levels and fetoplacental blood flow. STUDY DESIGN: Maternal and umbilical blood samples were collected in pregna ncies complicated by intrauterine growth restriction with abnormal umbilica l artery Doppler findings and in control pregnancies. Adrenomedullin levels were measured by means of a specific radioimmunoassay, and flow velocimetr y waveforms were recorded from uterine, umbilical, and fetal middle cerebra l arteries. RESULTS: Mean adrenomedullin values in umbilical plasma were higher (P < .0 5) in patients with intrauterine growth restriction (63.7 +/- 34.2 pg/mL; n = 16) than in control subjects (38.1 +/- 14.8 pg/mL; n = 16). A significan t correlation was found between maternal adrenomedullin levels and umbilica l artery pulsatility index. Moreover, fetal adrenomedullin concentrations c orrelated negatively with middle cerebral artery pulsatility index and posi tively with umbilical artery pulsatility index/middle cerebral artery pulsa tility index ratio. CONCLUSION: This study provides evidence that adrenomedullin is increased i n fetuses with intrauterine growth restriction in response to reduced utero placental blood flow and suggests that it may participate in the fetal hemo dynamic modifications.