X-rays, ultrasound, CT, MRI and other imaging tests have become an indispensable part of clinical medicine. Many parents-to-be worry that the “radiation” from these tests will harm the fetus, and some pregnant women, knowing that they have been “photographed”, bite the bullet and have an abortion in order to have a healthy baby. In addition, some doctors also wrong advice, resulting in these women also have to choose to abort. Also a little pregnant with a child, may be due to certain diseases or accidents need to use X-ray examination to make a correct diagnosis, many pregnant women panic on the fetus into adverse effects and give up to do X-ray examination. Exposure to radiation during pregnancy in the end has no effect on the fetus? Let’s take a look at the data to see if diagnostic tests can cause fetal damage or even teratology. The effects of X-rays on the embryo or fetus are as follows: 1. Miscarriage Within 33 days of pregnancy (calculated from the start of the last menstrual period of the pregnant woman) is the period of “all-or-nothing” response to external risk factors affecting the embryo or fetus. During this period, the embryo receives excessive X-rays and miscarriage can occur, but this type of very early miscarriage may not have obvious manifestations, also known as “biochemical pregnancy”, a woman may just feel that the menstrual period is delayed for a few days, and if a careful woman takes a urine test, she will find that HCG (chorionic gonadotropin) is positive; if there is no miscarriage, the risk of other problems with the fetus will not be significantly increased. If there is no miscarriage, the risk of other problems in the fetus does not increase significantly, i.e. there is usually no problem. 2, teratogenicity after 33 days of pregnancy to the end of the third month is a teratogenic sensitive period, during which a large number of fetal organs are concentrated development, but there are also some organs of teratogenic sensitivity will continue into the late pregnancy. Studies in Japan have found that pregnant women who were exposed to radiation after the atomic bombings of Hiroshima and Nagasaki were prone to give birth to babies with microcephaly, mental retardation, or other systemic developmental delays. Fetuses between 4 and 22 weeks of gestation are most susceptible to malformations from the effects of ionizing radiation. Theoretically, fetal malformations can occur when a pregnant woman receives a radiation dose of 5 to 15 rad. The radiation doses for common X-ray examinations are: X-ray chest radiograph is 0,00007rad for a single dose, and it takes 71429 shots to exceed the minimum standard of 5rad. X-ray chest X-ray radiation dose is about 5 to 10 times the chest film, to the most 10 times the calculation also need to take more than 7000 times before exceeding the standard. Dental X-ray examination is 0,0001rad for a single time, and it takes 50,000 times to exceed the standard. The barium enema X-ray examination is 3,986rad, and it takes two times to exceed the standard. Abdominal CT single for 2, 6rad, two times to exceed the standard. 3, cancer-causing X-rays can increase the risk of malignant tumors (such as childhood leukemia) in fetuses after birth. According to a study by the University of Oxford in the United Kingdom, compared with those who are not exposed to radiation, the risk of malignant tumors in early, middle and late pregnancy exposure to radiation is 3, 19 times, 1, 29 times, 1, 30 times. Note that this is a “relative risk” and since the incidence of malignant tumors is usually very low, e.g., 1 in 100,000, a 3-fold relative risk is only an increase in incidence to 3 in 100,000, which is actually still very low. Decision-making: Pregnant women who are aware of the risks of X-rays need to make their own choices about the risks of X-rays, and they would like their doctors to answer the question, “Can I have X-rays” or “Should I have a baby”? In this case, the doctor can only assess the risk, and it is generally impossible to answer the question of whether or not it will be okay, because the risk is a theoretical calculation, and there are only two possibilities, yes and no, for an individual. Doctors can never promise that the fetus will be absolutely fine, and the choice is ultimately made by the patient. There are 3 reasons for this: 1. Even if a pregnant woman does not take medication, receive radiation or other risk factors, there is still a “background risk”. For example, in the general population, the overall risk of spontaneous abortion, fetal malformation, fetal developmental abnormalities, children with malignant tumors, etc. reaches 286 per 1,000, and most of them are very early spontaneous abortions, which are often manifested as “delayed menstruation” or “irregular menstruation”, mostly in older women. Most of these are very early spontaneous abortions, often characterized by “delayed menstruation” or “irregular menstruation. If a pregnant woman is exposed to risk factors such as radiation, the overall risk of fetal abnormality is equal to the sum of the additional risk from radiation plus the “background risk”. Therefore, this issue needs to be analyzed objectively, and the cause of fetal problems cannot be attributed to radiation in general. 2. X-rays are not as scary as ordinary people think. Some studies have shown that after exposure to an exposure of 0,5 rad, the chance of adverse effects only increases by 0,17 per 1,000 on top of the original risk, i.e., about one in every 6,000 fetuses receiving this dose of X-ray radiation will have an adverse outcome as a result. 3. The question of whether to terminate the pregnancy. If the radiation dose to the fetus is grossly excessive, the doctor may recommend termination of the pregnancy, but this is very rare. The relevant guidelines from the American College of Obstetricians and Gynecologists say that X-ray exposure during pregnancy is not an indication for therapeutic abortion. In other words, doctors will not recommend therapeutic abortion or induction of labor because a pregnant woman has had an X-ray. Ultrasound and MRI: There is no risk of ionizing radiation. Ultrasound is a commonly performed test in obstetrics. Numerous studies have confirmed that ultrasound during pregnancy is safe and does not adversely affect the fetus. Prolonged, high-dose, high-frequency ultrasound irradiation can cause the phenomenon of cavitation of the gestational sac, but this is generally only found in animal model experiments, which is not the case with ultrasound used in the clinic, so there is no need to worry. MRI (magnetic resonance imaging), like ultrasound, is not radioactive and does not produce ionizing radiation. A few animal fetal studies have found that exposure to the magnetic field of MRI examinations during early pregnancy may be teratogenic, but there are also animal experiments that have found no effect, and there is no information on human experiments.