Relationship between head circumference and biparietal diameter

Head to tail and biparietal diameter are related, the larger the biparietal diameter, the longer the head circumference, the smaller the biparietal diameter, the smaller the head circumference, during pregnancy can be judged by the size of the biparietal diameter and head to tail, and whether the gestational age is consistent. At the same time, it can also be estimated whether the pregnant woman chooses normal labor or cesarean section.