The 35th day of gestation belongs to the early stages of pregnancy, which is a critical period for the development of the embryo, and therefore it is important to avoid drugs as much as possible in the early stages of pregnancy. During early pregnancy, the embryo gradually develops from a fertilized egg into a fetus with various tissues and organs. Some adverse factors in the early stages of pregnancy can affect the development of the embryo, causing malformations in fetal development and even the occurrence of miscarriage. According to the effects of drugs during pregnancy, drugs can be divided into three categories: safe drugs, relatively safe drugs, and prohibited drugs. During pregnancy, safe drugs can be taken without affecting the development of the embryo, but these drugs are rare. The next category is relatively safe drugs, which need to be taken or not during pregnancy depending on the needs of the condition. Due to medical ethics, relatively safe drugs have only been tested in animals, but there is a lack of confirmation of human trials. Therefore, the use of these drugs requires a balance between the advantages and disadvantages of their use. Finally, there are the prohibited drugs, which are not to be taken during pregnancy. Some components of these drugs can affect the development of the fetus. Therefore, if a prohibited drug is inadvertently taken, it is not recommended to keep this pregnancy. Therefore, the effects of drugs in early pregnancy need to be judged according to the class of the drug.