The sensory neuropeptide calcitonin gene-related peptide (CGRP) is a potent vasodilator that regulates inflammatory and immune responses and mediates vascular functions. In adults, CGRP level in blood is elevated during sepsis and/or shock. In these studies, we examined its potential role in neonatal and maternal inflammatory and vascular disturbances. A total of 189 samples (95 from cord blood and 94 from neonates) were collected within 12 hours of birth. The patients' gestational ages ranged from 24 to 43 weeks and the birth weights from 520 gms to 4445 grams. CGRP levels were measured by radioimmunoassay (RIA). Reverse phase-HPLC analysis of the immunoreactive CGRP present in adult and infant blood revealed that it coelutes with synthetic CGRP, confirming that the RIA is measuring authentic CGRP in human blood.

There is a developmental correlation of CGRP levels with a rise in gestational age and birth weight. The cord blood CGRP levels are significantly higher than those in the patient blood at term gestation (p<0.01), but not in preterm gestation. Infants were grouped according to gestational age (4 week intervals) or birth weights (500 gram intervals). CGRP levels in cord blood were significantly elevated in all groups when stressful conditions existed in the mother (29 of 95 samples, p<0.001). These included culture positive chorioamnionitis, thick meconium staining of amniotic fluid, placental abruption, severe oligohydramnios or severe pregnancy induced hypertension. There was a similar elevation in CGRP in patient blood (28 of 94 samples, p<0.001) in infants with culture positive sepsis/urinary tract infection, shock with blood pressure < 2 SD from the mean for corresponding gestation or congenital cyanotic heart disease. These results suggest that hemodynamic imbalance (eg., shock and heart disease) and inflammation (eg., sepsis) lead to an increase in CGRP levels in the circulation in neonates. This study was supported by grants from Wyeth Pediatrics and Children's Miracle Network.