Pelvic measurement is divided into external pelvic measurement and internal pelvic measurement. Most of the pelvic measurements of pregnant women during labor and delivery refer to the external pelvic measurement, which measures the outer diameter line of a woman’s pelvis with a specific ruler. This value does not have much significance for the delivery, because there are some pregnant women with good external pelvic measurement diameter line, but the middle pelvis or pelvic outlet is narrow, or not wide enough, and the fetus can not be delivered smoothly. Therefore, the external measurement is not very meaningful, so now the clinic has slowly abolished this examination means, now pay more attention to the internal pelvic measurement, the internal pelvic measurement is mainly the sciatic nodal interval diameter and pelvic exit angle. There are some pregnant women who cannot deliver even if their fetus is only 6 pounds or so and need a cesarean section, but the external pelvic measurements are fine and have a normal appearance because their pelvis is coalescing and is a male pelvis or ape-like pelvis that cannot deliver successfully. There are some pregnant women whose pelvis is not as wide as it looks, but they can deliver a heavier baby. There are some pregnant women who can’t deliver a baby of about 6 pounds because although the pelvis looks normal, the middle pelvis or pelvic outlet is narrow, which makes it impossible to deliver the baby smoothly. In other cases, the outer pelvis is not as wide, but the middle pelvis or exit is wide enough so that a fetus of 7 pounds or more can be delivered vaginally. Therefore, it is not necessary to perform external pelvic measurement before delivery, which is not clinically significant, but mainly depends on the size of the fetus and the mother’s pelvic coordination, as well as on the mid-pelvis and the exit, which mainly depends on the doctor’s assessment before labor or delivery after full term.