The normal human alanine aminotransferase is at 40 U/L, and alanine aminotransferase at 300 U/L in late pregnancy is more serious and requires prompt treatment. Aminotransferase is a type of liver enzyme, and the high limit of aminotransferase in the normal population, including pregnant women, is usually 40 U/L. Mild elevation of liver enzymes can be found in some people during pregnancy without any obvious cause, which is called pregnancy-induced liver damage. This elevation of liver enzymes is mild and usually has little effect on the mother or child. Moderate elevation of aminotransferase above 300 U/L, especially when accompanied by jaundice, is usually not caused by pregnancy, but may be due to other serious complications and comorbidities of pregnancy, such as preeclampsia, hellp syndrome, intrahepatic cholestasis in pregnancy, hepatitis due to viral infections, medications, etc., autoimmune disease-induced liver damage, and acute steatohepatitis in pregnancy. The rise of alanine aminotransferase to 300 U/L in late pregnancy is already more than seven times of the normal value, which may be due to a variety of reasons such as hepatitis, uterine compression, and biliary tract diseases. If the transaminases continue to rise, it means that the liver cells have been damaged, and in serious cases, it may cause cirrhosis and other conditions, so it is necessary to remain vigilant. Therefore, when a pregnant woman has a transaminase of 300 U/L in late pregnancy, she needs to consult a doctor in time, under the guidance of the doctor in order to clarify the specific causes of the disease, and give targeted treatment.