Adrenomedullin production is increased in normal human pregnancy

Objective: Adrenomedullin, a recently discovered vasoactive peptide origina lly identified in pheochromocytoma, has been found to be increased in the p lasma of pregnant women at term. This study was designed to elucidate wheth er adrenomedullin secretion is dependent on gestational age and the possibl e source and function of this peptide in human pregnancy, Study design: Adrenomedullin concentrations were determined by RIA in amnio tic fluid and maternal plasma obtained from 110 pregnant women between 8 an d 40 weeks of gestation. Subjects were stratified into five groups accordin g to gestational age. In term patients (n=15), adrenomedullin was also meas ured in the umbilical artery and vein separately, Results: High concentrations of adrenomedullin were present in plasma and a mniotic fluid samples from patients in the first, second and third trimeste r, There was no significant difference in mean maternal plasma concentratio n of adrenomedullin between the five patient groupings. Amniotic fluid adre nomedullin concentrations decreased from 81.2 +/- 11.7 pg/ml at 8-12 weeks of gestation to 63.7 +/- 6.0 pg/ml at 13-20 weeks of gestation and then inc reased at 21-28 weeks of gestation to 99.1 +/- 10.4 pg/ml. A further increa se was found in samples collected after 37 weeks of gestation (132.6 +/- 10 .1 pg/ml). In the umbilical vein, adrenomedullin concentration was higher ( P < 0.05) than in the artery (65.7 +/- 6.1 pg/ml and 48.5 +/- 5.2 pg/ml res pectively), suggesting that adrenomedullin in the fetal circulation derives from the placenta. Conclusions: Our results demonstrate the presence of adrenomedullin in mate rnal plasma and amniotic fluid throughout gestation, and show that its prod uction starts very early in gestation, suggesting that this hormone may hav e an important role in human reproduction, from implantation to delivery.