Amniotic fluid plays a critical role in fetal development. Amniotic fluid dynamics describe the production and elimination of amniotic fluid throughout gestation. Disruptions to this regulated system can lead to either increased amniotic fluid volume (AFV) for gestational age, polyhydramnios, or decreased AFV for gestational age, oligohydramnios. This chapter reviews the regulation of AFV throughout gestation, as well as the diagnosis, clinical significance, and management of each of these aberrations.