Background and aims Plasma concentrations of endothelin-1 (ET-1), a potent pulmonary vasoconstrictor with a short serum half-life, can be estimated by measuring its stable by-product, C-terminal pro-Endothelin-1 (CT-proET-1). To investigate the association between CT-proET-1, gestational age, and pulmonary morbidity in newborn infants.

Methods A prospective cross-sectional study at two tertiary university hospitals was conducted. CT-proET-1 concentrations (pmol/L) were determined in plasma samples of 293 newborn infants (gestational age 24–41 weeks) at birth and on day 3 of life with BRAHMS KRYPTOR automated immunoflorescent assay.

Results At birth, CT-proET-1 concentrations were unrelated to birth weight and gestational age. Venous umbilical cord CT-proET-1 concentrations were consistently higher than matched arterial ones (M 148 vs. 134 pmol/L, p<0.001), but both values were closely related (R_S=0.745, p<0.001). There was large postnatal increase of CT-proET-1 in infants with pulmonary morbidity. Days of mechanical ventilation, continuous positive airway pressure (CPAP), and oxygen supplementation correlated each with CT-proET-1 level on day 3 (R_S 0.566, 0.658, and 0.819, respectively, for all p<0.001).

Conclusions In term and preterm newborn infants, pulmonary compromise is associated with increased concentrations of circulating CT-proET-1.