Carbon 14 breath test test does not affect pregnancy. Carbon 14 breath test is one of the main methods for testing H. pylori and other gastric diseases, mainly applying the isotope labeling method, which has a certain degree of radioactivity, but as long as it is not a long-term exposure of medical personnel, one test has no effect on the body. It is recommended to prepare for pregnancy after six months. The radioactivity of carbon 14 is very weak and can be completely discharged within 48 hours, so there is no need to worry too much, but it is still necessary to take the initiative to conduct fetal examinations, genetic tests and amniotic fluid puncture during pregnancy to determine the health of the fetus, or you can prepare for pregnancy after the next menstrual cycle just in case. However, under normal circumstances carbon 14 breath testing is only a screening method and will not endanger your health, let alone reach the level of affecting your pregnancy.