GH2 (growth hormone 2), located on chromosome 17, encodes placental growth hormone (GH-V), a variant distinct from the pituitary growth hormone encoded by GH1 1. The GH2 gene is specifically expressed in the syncytiotrophoblast and extravillous trophoblast cells of the placenta, where it produces a protein differing from pituitary GH by 13 amino acids 2. During pregnancy, placental GH gradually replaces pituitary GH in maternal circulation from mid-gestation onward, becoming the predominant circulating form by term 23. GH2-encoded placental GH demonstrates high somatogenic activity and is secreted non-pulsatilely, functioning as a metabolic adaptor during pregnancy and playing a crucial role in physiologic adjustment to gestation, particularly in controlling maternal insulin-like growth factor-I levels 24. Genetic variants in GH2 (rs2006123) are significantly associated with adult height determination, indicating that placental growth hormone contributes to developmental programming of postnatal stature 5. While placental GH-V does not directly affect fetal growth due to its absence in fetal circulation, it may influence placental development through autocrine or paracrine mechanisms 2. GH-V secretion is inhibited by glucose and is significantly decreased in intrauterine growth restriction pregnancies 2, highlighting its clinical relevance in pregnancy complications and maternal metabolic health.