Insulin does not cause adverse effects on the fetus. Insulin is a hormone that can be secreted by normal human body. It is a protein hormone secreted by pancreatic beta cells in the pancreas stimulated by endogenous or exogenous substances, such as glucose, arginine and glucagon, etc. It is a macromolecular substance that cannot pass through the placenta and generally does not cause adverse effects on the fetus. When the blood sugar of pregnant women rises during pregnancy, it is better to use insulin early than late, and it should be used from the early stage of blood sugar rise, and it should start from a small dose. Untimely use may increase the probability of miscarriage and raise the risk of hypoglycemia and diabetes in the newborn. The amount of insulin should be controlled and the medication should be administered as prescribed by the doctor. Excessive use of insulin may cause pregnant women to have symptoms of hypoglycemia, such as impaired consciousness, dizziness, vertigo, headache, and hunger, etc. Eat foods with high sugar content, such as candy, as soon as possible at this time. When choosing insulin, you should try to use biosynthetic human insulin, because this insulin is closest to physiological insulin and generally does not stimulate the body to produce insulin antibodies. In addition, the regulation of blood sugar during pregnancy should not rely solely on insulin, and insulin treatment should be based on lifestyle adjustment. During insulin treatment, pregnant women should control the amount of food and exercise, maintain emotional stability and regular work and rest, and adjust the dose of insulin according to the blood sugar situation.