The safe threshold of acceptable radioactivity for the fetus is a radiation dose not exceeding 50 mSv. When the total radiation dose to the fetus reaches or exceeds the safety threshold, it may result in the occurrence of miscarriage, stillbirth, and fetal growth retardation. Occasionally, with a single chest or abdominal X-ray exposure, the radiation dose received by the fetus is much lower than the teratogenic amounts mentioned above. In addition, the organ-sensitive period of the embryo is the 5-11th week of menopause, which is the teratogenic-sensitive period, and is most likely to result in the development of birth defects when exposed to radiation exposure at this stage. Prior to this period, there is an “all or nothing” effect. If there is an effect, the embryo stops developing; if there is no effect, there is no increase in the incidence of birth defects.