The U.S. FDA has classified drugs into five levels according to their teratogenic effects on the embryo and fetus: A, B, C, D and X. A class is non-teratogenic drugs, such as moderate vitamins; B class can be used under the guidance of physicians, such as penicillin, erythromycin, digoxin, insulin, etc.; C, D and X class refer to adverse effects or teratogenic effects on the fetus, and their use is strictly prohibited during pregnancy. The anti-inflammatory drugs that we come into contact with in our daily life basically belong to class B. Short-term and low-frequency use is generally not significantly harmful to the embryo or fetus in the womb. If a pregnant woman takes anti-inflammatory drugs in early pregnancy, most of them have no effect on the fetus or have little effect if they are asymptomatic, so she can go to the hospital for relevant examinations. In the early stage of pregnancy, the effect of external factors such as drugs, radiation and external physical force on the embryo is “all or nothing”, in other words, if the above factors have an effect on it, there will be a miscarriage at that time; if everything is normal in the examination at that time, it means that the above factors have no effect on the fetus and the pregnancy can continue. The pre-fertilization period (usually within 2 weeks after fertilization) has little effect on the embryo; the post-fertilization period up to 12 weeks is the teratogenic period of drugs, at this time, any part of the cells are affected by toxicity may cause malformation, the earlier the toxic effect of drugs, the more serious the malformation may occur. Therefore, C, D and X grade drugs, such as drugs for treating tuberculosis, gynecological tumor, opioid psychotropic drugs, common promethazine, isoniazid, methotrexate, sleeping pills, drugs, etc., should not be used, and these drugs generally need to be taken for a long time and up to a certain amount before they have obvious teratogenic effects. However, the effects on undifferentiated organs such as the reproductive system and organs that continue to develop throughout pregnancy, such as the nervous system, remain. In conclusion, if you take anti-inflammatory drugs without knowing that you are pregnant, you can go to the hospital for a check-up and if the test results are normal, there is no need to worry too much. However, medication during pregnancy should be used with caution and a doctor should be consulted before taking any medication and should not be used on your own.