For most of the last decade, the field of growth disorders has evolved with more decisive signs of its detrimental potential to the health and development of fetuses, neonates, childhoods, and adults. This introductory chapter is, briefly, embracing themes on the growth disorders including growth hormone deficiency (GHD) and fetal growth restriction (intrauterine growth restriction (IUGR)). It then goes on to cover the effects of GHD or IUGR on different biological systems.
1. Harmful effects of GHD
The numerous actions of GH and insulin-growth factor-1 (IGF-1) play an important role in the health and development of offspring/individual [1, 2, 3, 4, 5, 6, 7]. The disorder in this axis/GHD during the development caused several complications including weight defect and developmental distortion [8, 9, 10, 11, 12]. A systemic GHD can induce hypersensitivity (mechanical and thermal) during the early postnatal period . Also, GHD can decrease the minerals in bones and increase the risk of fracture in adults . The harmful actions of GHD are reinforced in the presence of hypopituitarism [14, 15, 16].
2. IUGR and GH treatment (GHT)
On the other hand, IUGR disrupted the neurodevelopment processes (proliferation, migration, and maturation) [17, 18, 19, 20]. IUGR/GHD can cause fetal small for gestational age (SGA)  and increase the risk of cardiovascular, renal, visual, and mental diseases ; diabetes mellitus/obesity (increase in fat mass) [23, 24]; metabolic inflammation ; liver dysfunction ; mitochondrial imbalance (impair oxygen transport capacity) ; or immune problems [28, 29]. Moreover, GHD can delay the development and maturation of the male reproductive system  and the female reproductive system [31, 32]. The GHT is more effective on the female fertility , sperm efficiency , and mood and cognitive behavior in patients with GHD . The outcome results of GHT depend on the age, gender, body mass index (BMI), muscle/bone index, and waist circumference. However, studies of possible effects of GHT on the gonads (sperm/ova quality) and fetal growth patterns in pregnancy are scarce.
Thus, the current