The doctor’s words are always difficult to understand, and the mother-to-be is even more anxious, what do all those “professional terms” on the ultrasound sheets mean? What do those numbers mean? The most important thing to be concerned about is which of the many data? Generally speaking, we should be concerned about several indicators of fetal development, such as: biparietal diameter, head circumference, abdominal circumference and femur length; in late pregnancy, we should pay attention to indicators such as amniotic fluid index, placenta position and umbilical blood flow index. Biparietal diameter (BPD): the longest part of the head from left to right, also called the greater transverse diameter of the fetal head, is the longest part of the fetal head from left to right. It is used as a basis to estimate the weight and development of the fetus, to determine whether there is cephalopelvic asymmetry and whether the delivery can be successfully carried out. Huang Xiangling, Department of Ultrasound, Hainan Provincial People’s Hospital Occipital frontal diameter (OFD): the distance from the root of the fetal nose to the occipital ridge, also known as anterior-posterior diameter, is also the longest part of the fetal head from front to back, using this data to determine the fetal development and gestational week. Femoral length (FL): the length of the thigh, also called thigh bone length, which is the value of the longest part of the body. It is used together with the BPD (large transverse diameter of the fetal head) to calculate the weight of the fetus. Humerus length (HL): the length of the fetal upper arm bone, humerus length = -5.4282 + 0.7542 x biparietal diameter. Head circumference (HC): the length of the circumference of the head, also known as the circumference of the fetal head, is a value that measures the length of the head in one week. It is used to confirm the developmental status of the fetus. Abdominal circumference (AC): the length of the circumference of the belly, also known as the abdominal circumference, is a measurement of the length of the fetal belly. It is used together with APTD (anterior-posterior trunk diameter) and TTD (transverse trunk diameter) to estimate fetal development. Umbilical cord blood flow ratio (A/B): It is the blood flow in the umbilical cord. As the only channel for gas exchange, nutrient supply and metabolite elimination between the mother and the fetus, the hemodynamic changes in the umbilical cord can reflect certain pathological changes in the placenta, the fetus and even the mother, as well as certain high-risk pregnancy factors. The umbilical artery resistance index (RI) and the ratio of maximum systolic to maximum end-diastolic flow velocity (S/D), two hemodynamic indices representing the umbilical artery, are commonly used to detect the circulation and function of the placenta. In normal pregnancy, the S/D and RI values decrease as the gestational week increases and the fetal needs increase. Fetal position (LOA): It is a way of fetal head position and represents left occipital anterior position. Amniotic fluid index: It is the value obtained by adding the depth of amniotic fluid in the 4 areas, centered on the umbilicus of the pregnant woman and divided into 4 areas: upper, lower, left and right, during the ultrasound examination. Amniotic fluid dark zone: Under normal circumstances, the amniotic fluid zone observed in ultrasound is hypodense, so the maximum depth of the amniotic fluid dark zone is used clinically to indicate the deepest amount of amniotic fluid, which is normally 3~8 cm.