Acute Fatty Liver of Pregnancy

Updated: Mar 09, 2023
  • Author: Michael J Barsoom, MD, FACOG; Chief Editor: Ronald M Ramus, MD  more...
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Practice Essentials

Acute fatty liver of pregnancy (AFLP) is a serious complication unique to pregnancy first described by Sheehan in 1940. [1]  It is characterized by microvesicular steatosis in the liver. The foremost cause of AFLP is thought to be due to a mitochondrial dysfunction in the oxidation of fatty acids leading to an accumulation in hepatocytes. The infiltration of fatty acids causes acute liver insufficiency, which leads to most of the symptoms that present in this condition. If not diagnosed and treated promptly, AFLP can result in high maternal and neonatal morbidity and mortality.

Signs and symptoms

Patients with AFLP can present with the following:

  • Malaise

  • Nausea and vomiting

  • Right upper-quadrant and epigastric pain

  • Upper gastrointestinal hemorrhage

  • Acute renal failure

  • Infection

  • Pancreatitis

  • Hypoglycemia

  • Fulminant liver failure with hepatic encephalopathy

See Presentation for more detail.


Laboratory studies

The following laboratory results can be used to help make the diagnosis of AFLP:

  • Elevated aspartate transaminase (AST) and alanine transaminase (ALT) levels

  • Decreased blood glucose levels

  • Elevated levels of blood ammonia

  • Prolongation of prothrombin time, low fibrinogen, and low antithrombin levels

  • Elevated bilirubin levels

  • Elevated amylase and lipase levels in some patients

  • Elevated blood creatine and uric acid levels

Imaging studies

Imaging studies have a low sensitivity for diagnosing AFLP and should not be used to exclude the diagnosis.

See Workup for more detail.


Delivery of the fetus, regardless of gestational age, is the only treatment for AFLP once the diagnosis has been made.

See Treatment for more detail.



The exact pathophysiology of AFLP is unknown. AFLP is unique to pregnancy. [2] There does not appear to be a predilection for any geographical area or race. It appears to occur more commonly in primiparous women than multiparous women.

Women who develop AFLP are more likely to have a heterozygous long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) deficiency. LCHAD is found on the mitochondrial membrane and is involved in the beta oxidation of long-chain fatty acids. This gene mutation is recessive; therefore, outside of pregnancy under normal physiological conditions, women have normal fatty acid oxidation. However, if the fetus is homozygous for this mutation, it will be unable to oxidize fatty acids. [3] These acids are passed to the mother, who, because of diminished enzyme function, cannot metabolize the additional fatty acids. This results in hepatic strain leading to the development of AFLP, which can be relieved by delivery of the infant. [4, 5]



United States statistics

AFLP affects 1 in 7000 to 1 in 16,000 deliveries. There is a predilection for nulliparous women and women with multiple gestations. A male fetus is also a risk factor. [6]

Race-, sex-, and age-related demographics

No ethnic or regional variability is apparent.

This condition is unique to pregnancy and therefore only affects women.

This condition can affect any woman of child-bearing age.



The prognosis for women who develop AFLP is excellent, assuming they survive the acute event. However, a case of chronic pancreatitis has been described, occurring about 3 months after recovery and discharge from the hospital. [7]


Due to advances in diagnostic strategies and supportive care, maternal mortality and perinatal morbidity of AFLP has declined. In the 1980s, Kaplan reported a mortality rate for both mother and fetus of about 85%. [8]  Maternal mortality is now estimated to be 12.5-18%, with a neonatal mortality rate of 7-66%. [9, 10]

While laboratory abnormalities may persist after delivery, in rare cases patients may progress to hepatic failure with the need for liver transplantation. [11]

Morbidity of the infant includes increased risk of cardiomyopathy, neuropathy, myopathy, nonketotic hypoglycemia, hepatic failure, and death associated with fatty acid oxidation defects in newborns.


Life-threatening complications of AFLP include the following [6] :

  • Acute liver failure
  • Disseminated intravascular coagulation
  • Postpartum hemorrhage
  • Acute renal failure
  • Gastrointestinal bleeding
  • Hepatic rupture
  • Hepatic infarction

A study by Joueidi et al identified prognostic factors in AFLP. Prolonged prothrombin time was found to be a risk factor for maternal complications, and gestational age at delivery was associated with an increased risk of fetal and neonatal complications. [12]