Intrauterine growth restriction (IUGR) is defined as fetal growth slower than the normal growth potential of a specific fetus because of genetic or environmental factors. IUGR is associated with a high incidence of perinatal morbidity and mortality. IUGR neonates have a greater risk of hypoxic ischemic encephalopathy, intraventricular hemorrhage and necrotizing enterocolitis with longer hospital stay and higher health care costs. Incidence of a fetus developing a small size for gestational age is about 8%. Fetal growth is regulated by the balance between fetal nutrient demand and maternal placental nutrient supply. Intrauterine growth restriction may be caused by maternal, placental, or fetal factors. Nearly one-third of IUGRs are due to genetic causes, and two-thirds are related to the fetal environment. In the developing world, IUGR is likely to be a consequence of poor maternal nutritional status prior to or during pregnancy.