Acute and severe damage to the renal parenchyma caused by any reason, which causes the renal unit to lose its regulatory function, cannot maintain fluid and electrolyte balance, cannot excrete metabolites, and leads to hyperkalemia, metabolic acidosis and uremic syndrome, is collectively referred to as acute renal failure. The clinical manifestations of acute renal failure (ARF) are a series of physiological and biochemical changes such as decreased urine volume, metabolic disorders and uremia. The incidence of pregnancy complicated with ARF is low, about 0.02%~0.05%, but ARF during pregnancy is prone to develop into bilateral renal cortical necrosis and chronic renal failure, which is an extremely serious complication of obstetrics. About 2/3 of patients with ARF during pregnancy are caused by obstetric diseases. Most patients show oliguria (urine volume less than 400ml/d), or non-oliguric acute renal failure (urine volume more than 1000ml/d). However, regardless of the amount of urine, blood urea nitrogen and creatinine will increase progressively within a few days to a few weeks; in all patients with acute renal failure, urine chemical composition and (or) microscopic examination abnormalities may be found.