How to predict fetal weight?
summary
The parietal diameter is not the circumference of the head, but the length of the parietal diameter on both sides of the head; Abdominal circumference should be measured at the same plane of fetal liver and stomach; The big leg bone looks like a dog's favorite bone on ultrasound, and expectant mothers can observe it carefully through the ultrasonic display. Let's share my experience with you.
How to predict fetal weight?
Is the weight of the fetus the standard and what is the indicator? Who is it compared with? Lai Zongxuan, chief physician of Obstetrics and Gynecology, explained that the weight of the baby in the mother's stomach is compared with that of the fetus with the same number of weeks. Suppose a pregnant woman is 28 weeks pregnant. If you want to know whether her baby's weight is standard or not, you need to gather the expectant mothers who are also 28 weeks pregnant to calculate the average fetal weight in the abdomen among these pregnant women, and then compare the difference between this pregnant woman and this average value. Therefore, different weeks of pregnancy will lead to different average values.
However, it is impossible to gather the pregnant women of different gestational weeks in the world. Therefore, it is necessary to estimate the weight of the baby in the belly by statistical methods. Experts used ultrasound to measure 5000 pregnant women at 20, 24 and 28 weeks of gestation. After measuring the weight parameters of their babies, they drew a correlation curve with the number of weeks in the horizontal axis (x axis) and the weight in the vertical axis (Y axis). It can be clearly observed that the weight of the fetus is directly proportional to the number of weeks of gestation, and increases in a positive correlation.
Prenatal use of ultrasound to predict fetal weight, strictly speaking, is the prediction of weight drop point, so there will be errors. At present, the reasonable error is about half of the estimated value ± Assuming that the estimated weight is 2 000 g, then the weight drop point of the fetus should be 1 700-2 300 g, so as long as the baby's weight falls within this range after birth, even if the estimation is accurate.
matters needing attention
Because the measurement of fetal weight is calculated by the formula derived from the parameters, there is a range of error and applicable weeks. Dr. Lai Zongxuan believes that the error of fetal weight measured before 24 weeks is very large, so the prediction curve of fetal weight is not applicable to the fetus before 24 weeks. He suggested that expectant mothers should measure again in the middle and later stages of pregnancy, because it is only at this time that the fetal weight will be included in the evaluation index of growth and development, which is not only meaningful, but also more accurate.
