Maternal, placental, and fetal Insulin-Like Growth Factor-I (IGF-1) and IGF Binding proteins (IGFBPs) in Diabetic pregnancies: Effects on fetal growth and birth size.

Introduction: During gestation, IGF1 secretion and availability in the maternal blood and at the maternal-fetal interface is mainly regulated by IGF-binding proteins (IGFBP) such as IGFBP-1 synthesized by the decidua. Data about the interaction between maternal, placental, and fetal IGF1/IGFBP in relation to fetal growth and newborn size during diabetic pregnancy (gestational Diabetes (GDM) and Type 1 DM (T1DM) is not clear. Aim of the study and Methods: We reviewed the research papers published in Pubmed, Google scholar, Research gate, and Scopus in the past 20 years on the relationship between maternal, placental, and fetal/infantile/ IGF1/IGFBP-1 in relation to birth size in pregnancies associated with maternal diabetes. Results: Twenty-eight research papers were selected and reviewed (patients’ number = 1902). In GDM pregnancies, higher maternal IGF1 levels and/or its availability due to lower IGFBP1 levels can increase the size (weight) and functions of the placenta. These include the upregulation of specific placental amino acid transporter isoforms and GLUT-1, stimulation of mTOR signaling which stimulates protein synthesis, increasing mitochondrial functions, and accelerating nutrient transport which significantly contributes to fetal growth and newborn birth size. On the other hand, in pregnant women with T1DM, lower maternal IGF1 is associated with subsequent underweight placenta and lower birthweight.