The effects of high blood sugar of pregnant women on the fetus are as follows: 1. it can cause fetal cardiovascular malformation and neurological malformation; 2. the fetus cannot obtain relevant substances from amniotic fluid that are beneficial to lung development, thus causing poor lung development, resulting in susceptibility to neonatal respiratory distress syndrome, wet lung and pneumonia after birth; 3. it can cause huge babies or fetal growth restriction; 4. it can cause intrauterine hypoxia, resulting in intrauterine distress and even fetal death; 5. it can cause premature birth, miscarriage, embryonic development arrest and abnormalities.