The average biparietal diameter at 32 weeks is 85mm, which is normal and not large. The average of fetal biparietal diameter at 32 weeks of gestation is 81.7±6.5mm, which is the length of the widest part of the fetus between the left and right sides of the head, also known as the large transverse head diameter, and the fetal maturity is indicated when the biparietal diameter is >85mm as measured by ultrasound. The biparietal diameter is usually used clinically to observe the development of the fetus, to determine whether there is cephalopelvic disproportion, and whether the delivery can be successful. Generally, the biparietal diameter should be 93 mm or more at full term. At 32 weeks of gestation, when estimating the weight of the fetus, it is often necessary to measure the biparietal diameter to determine the size of the developing fetus, but this data is for reference only. During delivery, the largest diameter of the fetal head passing through the birth canal is the biparietal diameter, while the smallest diameter in the birth canal for the fetus to pass through is the transverse pelvic exit diameter, so if the biparietal diameter is larger than the transverse pelvic exit diameter, it may affect whether the fetus can be delivered naturally. Therefore, during pregnancy, pregnant women should pay attention to monitor the value of biparietal diameter, and if the value exceeds the normal range, they should control their diet appropriately, so as to facilitate the smooth delivery.