High serum leptin concentrations during catch-up growth of children born with intrauterine growth retardation

The aim of the study was to investigate how leptin could be involved in cat ch-up growth of children born with intrauterine growth retardation (IUGR). The study population was made up of 70 newborns with IUGR longitudinally st udied during the first 2 yr of life and 35 newborns and 32, 66, and 61 chil dren with normal birth weight aged 3 days, 12 months, and 24 months, respec tively. Postnatal patterns of body mass index (BMI) were similar in the 2 g roups, but BMI remained significantly lower in IUGR over the study period. In contrast, children born with IUGR aged 1 yr had significantly higher ser um leptin levels than normal children (P < 0.0001) independently of BMI. Th e correlation observed between BMI and serum leptin at birth in both groups and in the control group thereafter disappeared in children born with IUGR . Similarly, sexual dimorphism observed in normal children over the study p eriod was not observed in the IUGR group during the first 2 yr of life. In summary, serum leptin is effective and regulated during the first years of life as it is in older children. Children born with IUGR demonstrate high s erum leptin values during the first year of life, with a loss of the regula tory effect of BMI and gender. We suggest that these children develop an ad aptative leptin resistance beneficial for their catch-up growth. An alterna tive hypothesis is that these observations could reflect an adipocyte dysfu nction, a consequence of the special time course of adipose tissue developm ent in children born with IUGR.