Biparietal diameter of 59mm at 23 weeks of pregnancy is normal. 23 weeks pregnant in the middle of pregnancy, at this time the fetus is still in the critical period of growth and development, the standard value of the biparietal diameter of 58.8mm, due to the speed of fetal growth and development affected by genetic factors, nutrition and other factors, there are individual differences, it is generally believed that the standard value of the upper and lower standard deviation range of the value of the biparietal diameter of the normal range of the fetal biparietal diameter of the 23 weeks of pregnancy is between 53.9mm and 63.6mm. The normal range of fetal biparietal diameter at 23 weeks of pregnancy is between 53.9mm and 63.6mm. When the fetal biparietal diameter is significantly higher or lower than the standard level of pregnancy, you should consult a doctor to identify the cause of the disease, and if necessary, timely treatment to avoid adverse pregnancy outcomes.