Petry CJ, Burling KA, Barker P, et al. - Researchers wanted to see if there were any connections between maternal pregnancy circulating DLK1 (delta like non-canonical notch ligand 1) concentrations and maternal and fetal DLK1 genotypes, maternal insulin resistance and secretion and offspring size at birth. They assessed third-trimester maternal serum DLK1 concentrations and looked at how they contributed to parentally-transmitted fetal and maternal DLK1 genotypes, indices of maternal insulin resistance and secretion derived from 75g oral glucose tolerance tests performed around week 28 of pregnancy, and offspring size at birth in 613 pregnancies from the Cambridge Baby Growth Study. Maternal DLK1 concentrations were linked to the paternally-transmitted fetal DLK1 rs12147008 allele but not with maternal rs12147008 genotype. Such findings support a partial paternal or placental origin for maternal circulating DLK1, which may contribute to higher maternal circulating DLK1 concentrations, stimulation of maternal insulin resistance and compensatory hyperinsulinemia during pregnancy, and fetal growth promotion.