Up to 3 weeks of pregnancy is a safe period: If the drug is taken at this time without any signs of miscarriage, it generally means that the drug has not affected the fetus and the pregnancy can continue. 5-8 weeks of pregnancy is the hypersensitive period: At this time, the embryo is most sensitive to the effects of drugs, and unsafe use of drugs is most likely to lead to fetal malformation. At this time, we should judge whether to continue the pregnancy according to the size and symptoms of the toxic side effects of drugs. From 8 weeks to 4-5 months of gestation is the medium-sensitive period: this is the period when the fetal organs are further developed and mature, which is more sensitive to the toxic side effects of drugs and the degree of malformation is difficult to predict. If the pregnancy continues, amniotic fluid, umbilical cord blood and ultrasound should be done in the middle and late stages of pregnancy to monitor the fetal growth, and depending on the severity and prognosis, the pregnancy should be terminated or given in utero treatment as early as possible. At this time, the fetal organs are basically fully developed, so it is not easy to show obvious malformation after medication, but developmental abnormalities or limited damage may occur in varying degrees, such as streptomycin, kanamycin, quinine and quinidine may cause deafness.