Many women become pregnant unintentionally, thinking that it is due to “irregular menstruation” without realizing it, and in the meantime they happen to undergo X-ray medical examinations, such as fluoroscopy or chest X-rays during the physical examination at their workplace, and when they find out that they are pregnant, they are very worried about whether it will affect the fetus, and whether there is a need to terminate the pregnancy? The effect of X-rays on the embryo or fetus 1. Miscarriage Within 33 days of gestation (counting from the beginning of the last menstrual period of the pregnant woman) is the period of reaction to external risk factors affecting the embryo or fetus: during this period, miscarriage can occur when the embryo receives an excessive amount of X-rays, but this type of very early miscarriage may not have any obvious manifestations, also known as a “biochemical pregnancy,” which may just feel a delay in menstruation. Women may just feel menstruation delayed for a few days, careful women if the urine test will find HCG (chorionic gonadotropin) positive; if there is no miscarriage, the risk of other problems in the fetus will not increase significantly. 2, teratogenic After 33 days of gestation to the end of the third month is the sensitive period of teratogenicity, during which a large number of organs of the fetus concentrated development, but there are also some organs of teratogenicity sensitive period will continue to the end of pregnancy. Fetuses between 4 and 22 weeks of gestation are most susceptible to malformations caused by ionizing radiation. Theoretically, fetal malformations can occur when a pregnant woman receives a radiation dose of 5 to 15 rad. The following content high energy? The radiation dose of common X-ray examination is: X-ray chest film is 0.00007rad for a single time, it is necessary to take 71429 times in order to exceed the minimum standard of 5rad. the radiation dose of X-ray chest X-ray is about 5~10 times that of the chest film, and it is necessary to take more than 7000 times to exceed the standard by the calculation of the maximum 10 times. Dental X-rays are 0.0001 rad per dose, and it takes 50,000 times to exceed the standard. Barium enema X-ray single for 3.986rad, abdominal CT single for 2.6rad, 2 times to exceed the standard. 3, carcinogenic X-rays can increase the risk of malignant tumors (such as childhood leukemia) in fetuses after birth. Compared with those who are not exposed to radiation, the risk of malignant tumors is 3.19 times, 1.29 times, 1.30 times in the early, middle and late stages of pregnancy when receiving radiation. The incidence of malignant tumors is usually low. Some studies have shown that after exposure to 0.5 rad, the chance of adverse effects increases by only 0.017% over the original risk, i.e., about 1 in every 6,000 fetuses exposed to this dose of X-rays will have an adverse outcome as a result. Ultrasound is a commonly performed test in obstetrics. Ultrasound during pregnancy is safe and does not cause adverse effects on the fetus.MRI (Magnetic Resonance Imaging), like ultrasound, is not radioactive and does not produce ionizing radiation. In clinical practice, most of the MRI examinations are done when the pregnant women have other diseases, which need to be further identified and treated, and the routine examination such as ultrasound fails to confirm the diagnosis. At present, it is generally believed that MRI examination in late pregnancy is relatively safe, and MRI should be avoided as much as possible in the early stage of pregnancy.