Renal Aspects of Sodium Metabolism in the Fetus and Neonate

The transition from a growing fetus to a newborn infant requires many changes in fluid and electrolyte homeostasis. During gestation, the placenta controls this balance, but once the fetus is born, the kidneys will perform the task of regulating the excretion of water, electrolytes, and solutes, as well as nitrogenous waste products. This chapter will briefly review the factors that regulate the placental exchange of fluid and sodium, as well as the renal developmental changes that occur throughout the growth of the fetus and the subsequent adaptation to life outside of the womb, with a focus on the postnatal development of renal tubular transport.