Nine weeks of pregnancy is not the most dangerous period during pregnancy, but some risk factors do exist. Nine weeks of pregnancy belongs to the early stage of pregnancy, at this time the development of the embryo has taken on a human form, each organ is gradually differentiating and developing, the heart has been initially formed. This is a critical period of embryonic development, many drugs can act on the fetus through the blood barrier of the placenta, if improper use of drugs will affect the growth and development of the fetus, resulting in fetal deformity or miscarriage, so the use of drugs in this stage should be very careful, must be carried out under the guidance of the doctor, can not blindly use drugs. In addition, this stage of the fetus in the uterus is not yet particularly stable, the corpus luteum of pregnancy is gradually disappearing, the placenta is gradually formed, if the progesterone secreted by the placenta is unable to meet the normal demand of pregnancy, it is more likely to have a miscarriage. Therefore, in the ninth week of pregnancy, we must pay attention to rest, careful use of medication, avoid strenuous exercise and sexual life.