IMPLICATIONS: Mature adrenomedullin is a potent vasodilating peptide. We demonstrated that plasma-mature adrenomedullin concentration increased and that increased plasma-mature adrenomedullin is associated with increased blood volume during pregnancy.

Cardiac output, heart rate, and blood volume increase during pregnancy, whereas arterial blood pressure and vascular resistance decrease (1). Adrenomedullin is a potent vasodilating peptide isolated from human pheochromocytoma (2). It has been reported that plasma adrenomedullin concentration is increased in women in the later stages of pregnancy (3–5), and that this may play an important role in cardiovascular adaptation (6). Adrenomedullin is present in various tissues, including the central nervous system (7, 8), and it is possible that the cerebrospinal fluid (CSF) adrenomedullin is involved in regulation of maternal circulation.