Cord IGF-I concentrations in Indian newborns: associations with neonatal body composition and maternal determinants

BackgroundIndian newborns have been described as thin-fat' compared with European babies, but little is known about how this phenotype relates to the foetal growth factor IGF-I (insulin-like growth factor I) or its binding protein IGFBP-3. ObjectiveTo assess cord IGF-I and IGFBP-3 concentrations in a sample of Indian newborns and evaluate their associations with neonatal adiposity and maternal factors. MethodsA prospective cohort study of 146 pregnant mothers with dietary, anthropometric and biochemical measurements at 28 and 34 weeks gestation. Neonatal weight, length, skin-folds, circumferences, and cord blood IGF-I and IGFBP-3 concentrations were measured at birth. ResultsAverage cord IGF-I and IGFBP-3 concentrations were 46.6 (2.2) and 1269.4 (41)ngmL(-1), respectively. Girls had higher mean IGF-I than boys (51.4ngmL(-1) vs. 42.9ngmL(-1); P<0.03), but IGFBP-3 did not differ. Cord IGF-I was positively correlated with all birth size measures except length, and most strongly with neonatal sum-of-skin-folds (r=0.50, P<0.001). IGFBP-3 was positively correlated with ponderal index, sum-of-skin-folds and placenta weight (r=0.21, 0.19, 0.16, respectively; P<0.05). Of maternal demographic and anthropometric characteristics, only parity was correlated with cord IGF-I (r=0.27, P<0.001). Among dietary behaviours, maternal daily milk intake at 34 weeks gestation predicted higher cord IGF-I compared to no-milk intake (51.8ngmL(-1) vs. 36.5ngmL(-1), P<0.01) after controlling for maternal characteristics, placental weight, and newborn gestational age, sex, weight and sum-of-skin-folds. Sum-of-skin-folds were positively associated with cord IGF-I in this multivariate model (57.3ngmL(-1) vs. 35.1ngmL(-1) for highest and lowest sum-of skin-fold quartile, P<0.001). IGFBP-3 did not show significant relationships with these covariates. ConclusionIn this Indian study, cord IGF-I concentration was associated with greater adiposity among newborns. Maternal milk intake may play a role in this relationship.