Context: Copeptin is a stable by-product of arginine-vasopressin synthesis and reflects its secretion by the pituitary.
Objective: The objective of the study was to investigate perinatal factors affecting copeptin concentrations in preterm infants at birth and at 3 d of life.
Design and setting: This was a prospective cross-sectional study at two Swiss university hospitals.
Patients: One hundred sixty-seven preterm infants were enrolled, 59 infants born between 24 and 31 wk gestational age, 50 infants between 32 and 34 wk, and 58 between 35 and 36 wk.
Main outcome measure: Plasma copeptin concentrations, determined by a CT-proAVP-luminescence-immunoassay, were measured.
Results: Copeptin at birth was significantly higher in preterm infants born vaginally [median (range) 366 (1-2900) pmol/liter, n = 43] than those born by cesarean section [6.9 (2-1580), n = 124]. In infants born after cesarean without prior labor (n = 66), estimated fetal weight less than the fifth percentile, suspect fetal heart rate, compromised placental perfusion, and chorioamnionitis were each associated with significantly elevated cord copeptin. Copeptin at 3 d of life was not associated with cord blood copeptin but inversely related to gestational age (Rs = -0.6, P < 0.001) and birth weight (Rs -0.612, P < 0.001). Day 3 copeptin increased alongside the level of mechanical respiratory support.
Conclusion: Copeptin is a highly sensitive marker of perinatal stress.