Sexual disparity of copeptin in healthy newborn infants.

Abstract

Arginine vasopressin (AVP) regulates water balance and blood pressure and plays a role in social behavioral processes. Healthy adult men as compared with women have higher blood levels of AVP and its C-terminal precursor peptide, copeptin. The objective of the study was to investigate whether sexual disparity of copeptin is present at birth. In 241 prospectively enrolled healthy newborn infants, 131 boys and 110 girls, plasma copeptin concentrations were measured at birth and on day 3 of life. Multivariable linear regression analysis revealed stressful delivery (regression coefficient β = .569, P <0.001), acidosis (β = -.347, P < .001), and male gender (β = .132, P < .01) as independent determinants of copeptin at birth. In infants born without stress, that is by primary cesarean section (n = 81), male gender was the sole variable associated with copeptin (β = .286, P < .05), copeptin concentrations being higher in boys [median 5.5 pmol/L (interquartile range 4.4-10.2)] than in girls [4.8 pmol/L (interquartile range 3.6-5.8), P < .05]. At day 3 of life, copeptin was determined independently by postnatal physiological dehydration (β = .485; P < .001) and birth weight (β = .279; P < .01). Sexual disparity of copeptin is already present at birth, indicating increased activation of the AVP system in newborn boys as compared with girls.