Insulin has no 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 β-cells in the pancreas stimulated by endogenous or exogenous substances, such as glucose, arginine, glucagon, etc. It is a macromolecular substance, which can’t pass through the placenta, and it generally won’t have any adverse effect on the fetus. When pregnant women’s blood sugar rises during pregnancy, it is better to use insulin sooner rather than later, and it should be used from the early stage of blood sugar rise and start with a small dose. Untimely use may increase the probability of miscarriage and raise the risk of hypoglycemia and diabetes in the newborn. And the amount of insulin used should be controlled and the medication should be used as prescribed by the doctor. Excessive use of insulin can lead to symptoms of hypoglycemia in pregnant women, such as impaired consciousness, dizziness, vertigo, headache, hunger, etc. At this time, as soon as possible to eat foods with high sugar content, such as candy. When choosing insulin, you should try to use biosynthesized human insulin, because this kind of insulin is closest to physiological insulin, and generally does not stimulate the body to produce insulin antibodies. In addition, blood glucose regulation during pregnancy cannot 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, regular work and rest, and adjust the dosage of insulin according to the blood glucose situation.