Background/aim: Excessive fetal growth is associated with increased adiposity and reduced insulin sensitivity at birth. Copeptin, a surrogate marker of arginine vasopressin (AVP) secretion, is upregulated in states of hyperinsulinemia and is considered one of the mediators of insulin resistance. We aimed to investigate cord blood concentrations of copeptin (C-terminal fragment of AVP pro-hormone) in healthy large-for-gestational-age (LGA) infants at term.
Methods: This prospective study was conducted on 30 LGA (n=30) and 20 appropriate-for-gestational-age (AGA, n=20) singleton full-term healthy infants. Cord blood copeptin and insulin concentrations were determined by ELISA and IRMA, respectively. Infants were classified as LGA or AGA, based on customized birth-weight standards adjusted for significant determinants of fetal growth.
Results: Cord blood copeptin concentrations were similar in LGA cases, compared to AGA controls, after adjusting for delivery mode. However, in the LGA group, cord blood copeptin concentrations positively correlated with birth-weight (r=0.422, p=0.020). In the AGA group, cord blood copeptin concentrations were elevated in cases of vaginal delivery vs elective cesarean section (p=0.003). Cord blood insulin concentrations were higher in LGA cases, compared to AGA controls (p=0.036). No association was recorded between cord blood copeptin concentrations and maternal age, parity, gestational age or fetal gender in both groups.
Conclusions: Cord blood copeptin concentrations may not be up-regulated in non-distressed LGA infants. However, the positive correlation between cord blood copeptin concentrations and birth-weight in the LGA group may point to the documented association between AVP release and increased fat deposition. Vaginal delivery vs elective cesarean section is accompanied by a marked stress-related increase of cord blood copeptin concentrations.
Keywords: AVP; Copeptin; Cord blood; Fetal macrosomia; Insulin.
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