Published online by Cambridge University Press: 19 January 2021
The liver attains its highest relative size at about 10% of fetal weight at the ninth week of gestation. Early in gestation the liver is the primary site for hematopoiesis. At seven weeks of gestation, hematopoietic cells outnumber hepatocytes. Primitive hepatocytes are smaller than mature cells and are deficient in glycogen. As the fetus nears term, hepatocytes predominate and enlarge with expansion of the endoplasmic reticulum and accumulation of glycogen. Hepatic blood flow, plasma protein binding, and intrinsic clearance by the liver (reflected in the maximal enzymatic and transport capacity of the liver) also undergo significant postnatal maturation. These changes correlate with an increased capacity for hepatic metabolism and detoxification. At birth, the liver constitutes about 4% of body weight compared with 2% in the adult. Liver weight doubles by 12 months of age and increases three-fold by three years of age.