If you have high blood sugar in the fourth month of pregnancy, you should check your fasting blood sugar. If the blood sugar is not particularly high, but only slightly high, you should pay attention to controlling your diet, mainly by prohibiting sweets and controlling the intake of staple foods such as pasta. In order to ensure balanced nutrition, you can take a moderate amount of high quality protein, eat eggs, milk or lean meat, such as beef, pork and fish, in order to benefit the growth and development of the fetus. You also need to exercise in moderation and not to overexert yourself. If the blood sugar is too high in the fourth month, it will affect the growth and development of the fetus, resulting in abnormal development of pregnancy, miscarriage, premature birth, excessive amniotic fluid or even fetal death in the womb, or lead to a huge baby, and should be controlled by subcutaneous insulin injections under the guidance of a doctor.