The period during which the fertilized egg is implanted belongs to the period of insensitivity to drugs, and the effect of taking medication during this period on the development of the fetus follows the principle of all or nothing. If it has an adverse effect on the embryo, it will miscarry naturally, and if there are no symptoms of miscarriage such as vaginal bleeding or lower abdominal pain, it will have no effect on the embryo, which means that if symptoms of preeclampsia are present, fetal preservation is not recommended. The use of medication during this period generally does not lead to malformations, although it is not conducive to eugenics, and the taking of medication during the preparation for pregnancy and after pregnancy is subject to strict limitations, and medications that may adversely affect the embryo and lead to fetal malformations are not allowed to be taken. Drugs used during pregnancy are categorized according to the standards set by the U.S. Food and Drug Administration into A, B, C, D, and X levels according to the size of their safety, and X-rated drugs can never be used, such as ethinyl estradiol, thalidomide, and so on. The use of medication during pregnancy requires caution, and it is best to use medication under the guidance of a doctor.