Carbon 13 refers to the carbon 13 breath test, which is a non-invasive method for diagnosing H. pylori infection, with the advantages of fast detection, high accuracy and high safety. In general, breastfeeding a baby after a breastfeeding woman has had a carbon 13 breath test is not harmful to the mother or baby. Carbon 13 breath test is a test method in which the subject takes urea 13C orally. Urea will react with urea hydrolase secreted by Helicobacter pylori and decompose to form carbon dioxide, which then enters the lungs with blood circulation and is then eliminated from the body in the form of gas, to detect whether the gas has carbon 13 markers to diagnose the disease. Carbon 13 exists in nature and has no radioactive isotopes, so it is safe and generally has no effect on human and breast milk health, so there is no harm in breastfeeding your baby after doing a carbon 13 breath test. However, it should be noted that there is a small amount of radioactivity in the carbon 14 breath test, so it is not recommended for breastfeeding women to have a carbon 14 breath test. In addition, medications used to treat H. pylori, such as amoxicillin, clarithromycin, omeprazole, and colloidal bismuth pectin, may affect breastfeeding, and it is recommended to inform your doctor of your particular condition to ensure safe breastfeeding.