Acute Fatty Liver of Pregnancy (AFLP)

What happens in AFLP

In AFLP, tiny droplets of fat build up inside the liver cells (microvesicular fatty infiltration). The cells stop working properly, and liver function can fail within days. Because the liver makes clotting factors, clears toxins and maintains blood sugar, failure leads to bleeding problems, very low blood sugar, confusion and kidney injury.

The exact cause is not fully understood, but a strong link is known: some cases occur when the baby has an inherited problem processing fatty acids, most often LCHAD deficiency. The baby's unprocessed fatty acids cross back into the mother's circulation and overwhelm her liver. This is why babies of mothers with AFLP should be tested after birth.

Symptoms

AFLP usually begins between 30 and 38 weeks, but can occur earlier or be first recognized after delivery. Early symptoms are easy to mistake for normal pregnancy discomforts:

• nausea and vomiting, often the first sign
• loss of appetite and feeling generally unwell
• pain in the upper belly, especially on the right or under the breastbone
• headache and tiredness
• excessive thirst and passing a lot of urine (from a temporary form of diabetes insipidus)

As it progresses:

• jaundice (yellow skin and eyes), dark urine
• confusion, drowsiness or agitation from liver failure (hepatic encephalopathy)
• bleeding and bruising easily
• reduced urine output from kidney injury
• signs of preeclampsia, such as high blood pressure and swelling, in about half of cases

Risk factors

• first pregnancy
• twins or other multiple pregnancy
• carrying a male baby
• low body weight
• a baby with a fatty acid oxidation disorder, such as LCHAD deficiency
• preeclampsia or HELLP syndrome in the same pregnancy
• a previous pregnancy with AFLP

AFLP vs HELLP syndrome and other liver conditions

AFLP overlaps with other late-pregnancy liver conditions, and sometimes they occur together.

Viral hepatitis can also cause jaundice in pregnancy and is checked for during diagnosis.

Diagnosis

There is no single test. Doctors combine symptoms, examination and tests. Typical findings are:

• raised liver enzymes and bilirubin
• low blood sugar
• prolonged clotting times and low fibrinogen
• raised uric acid, ammonia and white cell count
• kidney function changes (rising creatinine)
• ultrasound that may show a bright, fatty liver, though it is often normal

Doctors often use a checklist called the Swansea criteria, which counts how many of these features are present. A liver biopsy is rarely needed because of bleeding risk.

Treatment

AFLP is a medical and obstetric emergency, managed by a team including obstetricians, maternal-fetal medicine specialists, intensive care and liver specialists.

• Prompt delivery: the only definitive treatment. Once the mother is stabilized, the baby is delivered by induction or cesarean section, regardless of gestational age.
• Correcting low blood sugar with intravenous glucose.
• Correcting clotting problems (disseminated intravascular coagulation) with blood products such as plasma, cryoprecipitate and platelets before and after delivery.
• Supportive intensive care: fluids, monitoring of kidney and liver function, and treating infection.
• Dialysis for severe acute kidney injury.
• Liver transplant: very rarely needed when the liver does not recover.

Complications

• liver failure and hepatic encephalopathy
• DIC and heavy bleeding
• kidney injury
• low blood sugar
• pancreatitis
• infection
• for the baby: preterm birth, distress, and complications related to the mother's illness

Outlook

Liver function usually starts to improve within days of delivery and returns to normal within weeks. With early recognition, prompt delivery and modern intensive care, most mothers survive and recover without lasting liver damage, though AFLP remains serious. Babies are tested for fatty acid oxidation disorders, which need lifelong dietary management if confirmed.

Future pregnancies

AFLP can recur in future pregnancies, especially if the baby has LCHAD deficiency. Genetic counseling and close monitoring with regular liver tests in later pregnancies are recommended.

Frequently asked questions

What are the first symptoms of acute fatty liver of pregnancy?

The first symptoms are usually nausea, vomiting, loss of appetite and feeling unwell in the third trimester, often with upper belly pain, headache and excessive thirst. Jaundice, confusion and bleeding follow. New vomiting after 28 weeks should always be checked.

What causes AFLP?

The exact cause is not fully known. Many cases are linked to the baby having an inherited fatty acid processing disorder, such as LCHAD deficiency, which overloads the mother's liver. First pregnancies, twins and carrying a boy also raise the risk.

How is acute fatty liver of pregnancy treated?

The treatment is to stabilize the mother and deliver the baby as soon as safely possible. Intensive care corrects low blood sugar, clotting problems and kidney failure. Most mothers' liver function improves within days of delivery.

Can AFLP happen again?

Yes, it can recur in later pregnancies, particularly when the baby has a fatty acid oxidation disorder. Anyone who has had AFLP should get genetic counseling and close monitoring with blood tests in future pregnancies.