Pregnancy changes many blood tests, but it doesn’t push the main liver enzymes far out of range, so a clearly high result is worth explaining. The causes fall into two groups: conditions that only happen in pregnancy, and ordinary liver problems that can happen to anyone. How far along you are is the strongest clue, because each pregnancy-specific condition tends to appear at its own stage.1PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review Most causes are mild and fade once the baby is born, while a small number need care within hours, so the test that comes next matters as much as the first result.
Which Liver Test Changes Are Normal in Pregnancy
Some results that look abnormal on your report are expected. Alkaline phosphatase (ALP) is an enzyme made by the liver and bone, and in pregnancy the placenta makes it too, so it is often high by the third trimester.2PubMed. Liver function tests in normal pregnancy: a prospective study of 103 pregnant women and 103 matched controls Albumin, a blood protein, tends to read low throughout pregnancy because your expanded blood volume dilutes it.3PubMed. Liver function tests in normal pregnancy: a prospective study of 103 pregnant women and 103 matched controls Bilirubin and GGT, another liver marker, usually run lower than before pregnancy.4PubMed. Liver function tests in normal pregnancy: a prospective study of 103 pregnant women and 103 matched controls Reddened palms and small spider-like veins on the skin are also usually harmless pregnancy changes.5Cleveland Clinic Journal of Medicine. The liver in pregnancy: Disease vs benign changes Lab ranges are written for adults who aren’t pregnant, so ask which flagged values your doctor considers normal for you.
ALT and AST are the exception. These are the enzymes most labs mean by “liver enzymes,” and they leak out of liver cells when the cells are irritated or damaged. In healthy pregnancies they stay about the same as in women who aren’t pregnant, with only a tiny, still-normal rise in ALT in the second trimester.6PubMed. Liver function tests in normal pregnancy: a prospective study of 103 pregnant women and 103 matched controls So a high ALT or AST shouldn’t be put down to “just pregnancy.” Many doctors treat values above 40 IU/L as raised in pregnancy.7PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review A level two or three times the upper limit is a mild rise, while levels in the hundreds point to more serious causes.
A single mildly raised result is often simply repeated, because a lab value can shift with recent hard exercise, a new medicine or ordinary lab variation. If the repeat is still raised, or the first result was clearly high, the next step is usually a wider panel that adds bilirubin, a blood count, platelets and kidney tests.
Early Pregnancy Cause, Severe Vomiting
Severe pregnancy vomiting, which doctors call hyperemesis gravidarum, is relentless vomiting in early pregnancy that causes dehydration and loss of more than 5% of your pre-pregnancy weight.8PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review Liver enzymes rise in about 8 to 15% of these women, and in up to 40 to 50% of those sick enough to be admitted to hospital.9PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review The rise is usually mild, about two to five times the upper limit, and yellowing of the skin is rare.10PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review Dehydration, poor nutrition and acid build-up from not eating are thought to strain the liver.11Netherlands Journal of Medicine. Liver enzyme elevation induced by hyperemesis gravidarum: aetiology, diagnosis and treatment High levels of the pregnancy hormone hCG may also play a part.12PubMed Central. Electrolyte imbalance and liver function test abnormalities among pregnant women with hyperemesis gravidarum at Wag-himra zone public hospitals, Northeast Ethiopia, 2023: a comparative cross-sectional study
Treatment for severe pregnancy vomiting means fluids, often through a drip, anti-sickness medicine and help to start eating again. Enzymes usually fall as you rehydrate and keep food down.
Doctors usually check electrolytes such as sodium and potassium, and kidney function, alongside liver tests, since dehydration affects all of them. Urine may be checked for ketones, which appear when the body burns fat because it isn’t getting enough food. Bilirubin is usually normal or only slightly raised, so a clearly raised bilirubin points away from vomiting alone.
If levels are very high, or your eyes turn yellow, doctors look for other causes such as hepatitis or medicines. Enzymes that don’t fall as the vomiting improves also call for more tests.
Prolonged vomiting can leave you short of vitamins such as thiamine, so doctors may add vitamin supplements. Keep a note of how much you can drink and how often you vomit to share with your clinician.
Itching Later in Pregnancy, Cholestasis of Pregnancy
Cholestasis of pregnancy slows the flow of bile out of the liver, causing itching, raised liver enzymes and raised bile acids, the digestive substances the liver makes.13PubMed Central. Review of a challenging clinical issue: Intrahepatic cholestasis of pregnancy It is the most common pregnancy-related liver disease, affecting about 0.1 to 1.5% of pregnancies.14PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review About 80% of cases begin after week 30.15PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review It is diagnosed when you have itching and a bile acid level above 10 µmol/L; some labs use 19 µmol/L if you have eaten before the test.16PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review17PubMed. AGA Clinical Practice Update on Pregnancy-Related Gastrointestinal and Liver Disease: Expert Review Hormones, genes and environment all contribute, and some women carry changes in bile-transport genes.18PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review19PubMed Central. An expanded role for heterozygous mutations of ABCB4, ABCB11, ATP8B1, ABCC2 and TJP2 in intrahepatic cholestasis of pregnancy
The itching is often worst on the palms and soles and tends to get worse at night. There is usually no rash, which sets it apart from pregnancy rashes. If you itch in late pregnancy without an obvious cause, call your midwife or maternity unit that day rather than waiting for the next scheduled visit, and ask specifically for bile acids and liver tests, since normal blood work from earlier in pregnancy doesn’t rule out cholestasis that has begun since. Itching can come before the blood tests turn abnormal, so a normal first result with ongoing itching often means repeating the tests.
Stillbirth risk tracks bile acid levels, not ALT.20PubMed. Association of adverse perinatal outcomes of intrahepatic cholestasis of pregnancy with biochemical markers: results of aggregate and individual patient data meta-analyses Below 100 µmol/L, stillbirth stayed rare, at roughly 1 to 3 in 1,000.21PubMed. Association of adverse perinatal outcomes of intrahepatic cholestasis of pregnancy with biochemical markers: results of aggregate and individual patient data meta-analyses At 100 µmol/L or above, about 3.4% of pregnancies ended in stillbirth.22PubMed. Association of adverse perinatal outcomes of intrahepatic cholestasis of pregnancy with biochemical markers: results of aggregate and individual patient data meta-analyses Levels of 40 µmol/L and higher make it more likely that the baby passes its first stool into the waters.23PubMed Central. Predictors of adverse neonatal outcomes in intrahepatic cholestasis of pregnancy So doctors usually offer ursodeoxycholic acid tablets, which ease the itching, and plan the timing of delivery around your bile acid level.24PubMed. AGA Clinical Practice Update on Pregnancy-Related Gastrointestinal and Liver Disease: Expert Review
Itching relief may take days to build. Because the stillbirth risk follows bile acids, feeling less itchy doesn’t by itself mean the risk has fallen, which is why doctors keep checking bile acids.
Expect bile acids to be rechecked every week or two, with higher levels leading to an earlier planned delivery. Cholestasis of pregnancy clears after birth.
Preeclampsia and HELLP Syndrome
Preeclampsia is new high blood pressure after 20 weeks together with signs of strain on other organs.25PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review AST or ALT above 40 IU/L counts as one of those signs.26PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review The workup includes blood counts, platelets, kidney tests, liver enzymes, a urine protein test and checks on the baby.27PubMed Central. Educational Case: Hemolysis elevated liver enzymes and low platelets (HELLP syndrome)
Preeclampsia is thought to begin in the placenta, which releases substances that disturb the lining of blood vessels throughout the body. Those changes reduce blood flow to organs, and in the liver this can injure cells and release ALT and AST. That is why raised enzymes in preeclampsia are treated as a sign of organ strain rather than a separate liver disease.
Blood pressure is measured at every prenatal visit because preeclampsia can develop without symptoms you would notice. A single raised reading is usually repeated after resting, and a persistent high reading triggers further tests. If your clinician offers a home cuff, record readings as asked and report high ones promptly. Go to labour and delivery triage the same day if a high reading comes with any of these: pain under the right ribs or in the upper middle of the belly, a severe headache that won’t go away, blurred vision or seeing spots, or sudden swelling of the face or hands.
HELLP syndrome stands for breakdown of red blood cells, elevated liver enzymes and low platelets, and doctors treat it as an emergency.28PubMed Central. Liver diseases in pregnancy Management centres on planning delivery.29PubMed. AGA Clinical Practice Update on Pregnancy-Related Gastrointestinal and Liver Disease: Expert Review In rare cases, bleeding forms under the liver’s outer layer and can rupture.30PubMed Central. Grade III subcapsular liver hematoma secondary to HELLP syndrome: A case report of conservative management Daily low-dose aspirin from week 12 is advised for women at risk of preeclampsia.31PubMed. AGA Clinical Practice Update on Pregnancy-Related Gastrointestinal and Liver Disease: Expert Review Five years after HELLP, about a third of women had developed high blood pressure, so long-term checks matter.32PubMed. Long-term maternal and subsequent pregnancy outcomes 5 years after hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome
Acute Fatty Liver of Pregnancy
This condition affects about 1 in 10,000 to 1 in 20,000 pregnancies, in the third trimester or just after birth.33PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review AST and ALT often reach 300 to 1,000 IU/L and bilirubin is usually above 5 mg/dL.34PubMed Central. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review Some babies carry an inherited problem breaking down fats, and the fatty by-products build up in the mother’s blood.35PubMed Central. Mitochondrial Dysfunction and Acute Fatty Liver of Pregnancy36PubMed Central. Acute fatty liver of pregnancy: An update on pathogenesis and clinical implications Treatment is prompt delivery, and most blood tests return to normal within 7 to 10 days afterwards.37PubMed. AGA Clinical Practice Update on Pregnancy-Related Gastrointestinal and Liver Disease: Expert Review38PubMed. Acute fatty liver of pregnancy: clinical outcomes and expected duration of recovery
It often starts with nausea, vomiting and belly pain late in pregnancy. Yellowing of the skin or eyes, unusual thirst or confusion can follow. These symptoms mean emergency care, not waiting for the next appointment.
Blood tests often show low blood sugar, and clotting problems may appear, which helps separate it from other causes of raised enzymes. Diagnosis comes from the combination of symptoms and blood results, and doctors may not wait for a liver scan or biopsy before acting. It can overlap with preeclampsia, and some women have features of both, so doctors check for both at once.
Care is often given in a high-dependency or intensive care setting because blood sugar and clotting need close monitoring. Women are usually watched closely after birth until blood tests and symptoms are clearly improving.
Because the cause can lie in the baby, doctors may test the newborn for a fat-processing disorder. Diagnosing it early lets the baby’s feeding be managed.
Causes That Aren’t Specific to Pregnancy
Non-alcoholic fatty liver may affect 16 to 18% of pregnant women.39PubMed. Implications of abnormal liver function in pregnancy and non-alcoholic fatty liver disease It probably explains most raised enzymes that have no other obvious cause, and it is linked to pregnancy complications.40PubMed. Implications of abnormal liver function in pregnancy and non-alcoholic fatty liver disease It usually causes no symptoms, so it often turns up only because of a routine blood test. Pregnancy is not the time for strict dieting, so ask your clinician about sensible food and activity advice and about blood sugar checks. After the birth, enzyme levels are often rechecked, and persistent raised levels warrant ongoing care.
Hormones slow the gallbladder, so up to 10% of pregnant women have gallstones.41Hepatology. It Takes Two: Liver diseases of pregnancy A stone that blocks the bile duct can raise enzymes and cause pain. Many gallstones cause no trouble, and pain typically comes in attacks after meals, often fatty ones, in the upper right belly. Fever, yellowing of the skin or eyes, or pain that doesn’t ease needs urgent assessment, since a blocked bile duct or infection can be serious. Many women are managed with pain relief and diet changes, with surgery when needed. Gallstones and HELLP both cause pain under the right ribs, so don’t assume the pain is your gallbladder; blood pressure, platelet and liver test results help tell them apart.
Acetaminophen (paracetamol) overdose is the top cause of acute liver failure in pregnancy, at about 30% of cases.42American Association for the Study of Liver Diseases. It Takes Two: Liver diseases of pregnancy Some blood pressure, thyroid, HIV and tuberculosis medicines and some antibiotics have caused liver injury, usually in the first 20 weeks.43PubMed. Drug-induced liver injury in pregnancy Most of these cases clear up on their own once the medicine is stopped.44PubMed. Drug-induced liver injury in pregnancy Keep to the dose on the label and never take more than one product containing acetaminophen at once.
Hepatitis A usually clears with good outcomes.45PubMed. Update on viral hepatitis in pregnancy Hepatitis E can be severe in the third trimester.46PubMed. Viral hepatitis in pregnancy: integrating clinical management, perinatal outcomes, and long-term health impact Hepatitis B and C are usually long-term infections that can pass to the baby.47PubMed. Viral hepatitis in pregnancy: integrating clinical management, perinatal outcomes, and long-term health impact Autoimmune hepatitis usually calms in pregnancy, but it can rarely flare.48AIHA – Autoimmune Hepatitis Association. Autoimmune Hepatitis and Pregnancy
To sort these out, an ultrasound, which is safe in pregnancy, can show gallstones and fat in the liver. Blood tests for hepatitis viruses are routine for unexplained raised enzymes. Expect to be asked about every medicine and supplement you take.
What Happens After a High Result
Expect more blood tests and probably an ultrasound.49PubMed Central. Liver diseases in pregnancy Serious causes are managed by a team including obstetricians, liver specialists and midwives.50PubMed Central. Liver diseases in pregnancy Most pregnancy-specific causes improve after delivery.51PubMed. Acute fatty liver of pregnancy: clinical outcomes and expected duration of recovery Fatty liver has been linked to diabetes during pregnancy and problems with blood sugar after it.52PubMed. Relationship between non-alcoholic fatty liver disease during pregnancy and abnormal glucose metabolism during and after pregnancy So ask for your liver tests and blood pressure to be rechecked after the birth.
Repeat tests are scheduled at intervals set by the likely cause: closer for suspected cholestasis or preeclampsia, and slower for mild unexplained rises. If enzymes keep rising or new symptoms appear, doctors may bring tests forward or admit you for monitoring. A cause that remains unclear may lead to a referral to a liver specialist during pregnancy or afterwards.
Useful questions for your doctor: Which cause is most likely at my stage of pregnancy? Do I need a bile acid test or a blood pressure check? When will the tests be repeated? Which symptoms should send me to hospital? After preeclampsia or HELLP, ask about aspirin from 12 weeks next time, and share your history early, at your first prenatal visit.