Developments in fetal and placental nutrition have highlighted the interaction of the placenta and fetal liver for the exchange and metabolism of nutrients. Of particular importance is the exchange of serine and glycine and their interconversion within these two organs and the exchange of glutamine and glutamate. Placental metabolism of nutrients and the placenta's role in the production and utilization of certain amino acids alters significantly the delivery rate of nutrients into the fetal circulation. Postnatal nutrition has focused on the role of early nutritional intervention in the extremely low birth weight infants and the recognition of the category of semi-essential amino acids in these infants. The role of minimal enteral feedings in small babies and the changes in nutritional requirements induced by medical complications has also received increasing attention.