Fetal biparietal diameter of 9.2cm at 33 weeks of pregnancy may be caused by over-nutrition of the pregnant woman, gestational diabetes, or fetal hydrocephalus. Generally speaking, the normal biparietal diameter of a fetus at 33 weeks of pregnancy is 8.2cm, and if the biparietal diameter of a fetus is 9.2cm, the fetus is considered to be oversized. Fetal macrosomia at 33 weeks of pregnancy may be caused by excessive nutritional intake during pregnancy, resulting in rapid fetal development, which is a normal physiological phenomenon and can be left untreated. If gestational diabetes mellitus occurs during pregnancy, it may lead to a huge baby, so the fetus at 33 weeks of pregnancy will have a fetal biparietal diameter of 9.2 cm. In addition, hydrocephalus in the fetus may also lead to a large head, so pregnant women have a biparietal diameter test at 33 weeks of pregnancy, the test result may also be 9.2 cm. It is recommended that pregnant women who find a 9.2cm biparietal diameter during the 33-week checkup need to go to the hospital in time to have the cause of the disease clarified and follow the doctor’s instructions for treatment.