Fetoprotein 300ng/mL is higher than normal, whether the condition is serious or not is mainly related to the cause of the disease, including physiological elevation during pregnancy, liver cancer and other pathological elevation. Fetoprotein is mainly synthesized by fetal liver cells and yolk sac, and it can be significantly elevated during pregnancy, which is a normal physiological phenomenon and the condition is not serious. It can gradually decrease after the end of pregnancy and does not need special treatment. However, if you have hepatocellular carcinoma, the liver will secrete alpha-fetoprotein again when the cancer cells divide, which will lead to obvious elevation. Hidden pain in liver area, abdominal distension and other uncomfortable symptoms often appear, which is when the condition is more serious and suggests tumor or tumor recurrence and active stage, etc. Alpha-fetoprotein is a specific indicator that can reflect the severity of liver cancer, and it should be treated with surgery as early as possible to prevent the condition from worsening. Besides, elevated alpha-fetoprotein can also be seen in some patients with rheumatic immune system diseases or serious infections, which may be related to their disease activities. It is recommended that the patient undergoes a complete workup to exclude neoplastic diseases and to monitor the changes in alpha-fetoprotein dynamically.