Background/aim Intrauterine growth restriction (IUGR) causes adaptations that program future propensity to obesity-related metabolic diseases, partly due to mitochondrial dysfunction in skeletal muscle, which is the major site of postprandial glucose disposal. Furthermore, IUGR fetuses present with compromised thermoregulation and susceptibility to hypothermia at birth, due to diminished insulation of subcutaneous adipose tissue. Irisin has recently been introduced as a novel myokine, which induces browning of the subcutaneous adipose tissue and consequent thermogenesis, while improving glucose metabolic parameters, such as insulin sensitivity and signalling. We aimed to prospectively investigate fetal circulating irisin concentrations in IUGR versus normal pregnancies and correlate them with various perinatal factors.

Subjects and methods Plasma irisin concentrations were determined by ELISA in 50 mixed arteriovenous cord blood samples from IUGR (n = 30) and appropriate-for-gestational-age (AGA, n = 20) singleton full-term pregnancies.

Results Fetal irisin concentrations were lower in IUGR cases, compared to AGA controls (p = 0.031). No association was recorded between cord blood irisin concentrations and maternal age, parity, gestational age, delivery mode or fetal gender in both groups.

Conclusions The well-documented impaired skeletal muscle metabolism and mitochondrial dysfunction in IUGR fetuses may account for their irisin deficiency, which may be part of the fetal programming process, leading to increased susceptibility to later development of obesity and related metabolic disorders. Furthermore, irisin down-regulation may represent an additional mechanism underlying the susceptibility of IUGR infants to hypothermia at birth, by inducing less “browning” of their already diminished subcutaneous adipose tissue and consequently less non-shivering thermogenesis at birth.