What does fetal biparietal diameter mean?

Double diameter vertex, also known as fetal head double vertex diameter, refers to the length of the widest part between the left and right sides of the fetal head, also known as the "head big transverse diameter". B ultrasound measurement of double diameter vertex greater than 8.5 indicates fetal maturity. Generally, fetal development is observed by measuring fetal double diameter vertex, and whether the pregnant woman is not head and pelvis. At full term pregnancy, it should reach 9.3 cm or more. According to the general rule, after the fifth month of pregnancy, it basically coincides with the month of pregnancy, that is, the double diameter apex is about 7.0 cm at the 28 th week of pregnancy, about 8.0 cm at the 32 th week of pregnancy, and so on.