Introduction to fetal biparietal diameter standards and their significance at 34 weeks of pregnancy 34 weeks of pregnancy is an important period of fetal development, and biparietal diameter is one of the important indicators for evaluating fetal development. This article will introduce in detail the concept of fetal biparietal diameter, the standard of fetal biparietal diameter at 34 weeks of pregnancy, the significance of biparietal diameter, and how to scientifically evaluate fetal development. 1. The concept of fetal biparietal diameter. Fetal biparietal diameter refers to the distance between the two poles of the fetal head, that is, the diameter at the largest head circumference. It is generally used as BPD (Bipa).