Calculate fetal weight based on uterine height and abdominal circumference

We all know that the physical health of pregnant women during pregnancy is of great concern. Pregnant women will have regular prenatal checkups because they need to always observe whether the baby in their body is growing healthily. The examination can determine what nutrients the baby needs during the growth process. Many doctors will calculate the weight of the fetus based on the pregnant woman's uterine height and abdominal circumference. How is it calculated? Let’s take a look below.

1. Fetal weight (g) = -2686.60 + 171.48 × abdominal circumference;

2. Fetal weight (g) = 2900 + 0.3 × uterine fundus height × waist circumference;

3. Fetal weight (g) = -5168.32 + 100.97×head circumference + 110.86×abdominal circumference + 143.09×femur length + 331.43×fetal leg subcutaneous fat thickness;

The above method is an estimate and does not represent the actual weight of the baby at birth. The purpose of predicting fetal weight is to detect problems in fetal development as early as possible. Generally speaking, there will be a plus or minus 10% to 15% error between the actual weight at birth and the predicted weight. For example, if the birth weight is 4000 grams, the error range will be 400 grams. In other words, the heavier the baby, the greater the margin of error.

Palace height effect

1. Assess fetal development. Measure the height of the uterine fundus and plot the results on a pregnancy chart to see if fetal development is consistent with gestational age. If you find that the baby's pregnancy rate is inconsistent with the gestational age, or is too large or too small, you need to look for the cause, such as doing special examinations such as B-ultrasound to determine whether there are twins, deformities, stillbirths, too much or too little amniotic fluid, etc.

The purpose of doctors regularly checking pregnant women's uterine height and abdominal circumference is to gain a general understanding of the intrauterine development of the fetus through the pregnant woman's individual data. It should be noted that if the uterine height does not change for two consecutive weeks, the pregnant mother must go to the hospital immediately for treatment.

2. Estimate the due date. Another function of measuring uterine height is to predict the due date of delivery. Generally speaking, the curve of fetal uterine height changes first rises and then falls. At the end of the 4th month of pregnancy, the height of the uterine fundus is 10cm above the pubic symphysis. It continues to rise until the end of the 9th month of pregnancy, when it rises to 28-30cm above the pubic bone. However, by the end of the 10th month of pregnancy, the height of the uterine fundus will return to the height at 8 months. That is to say, as the time of birth approaches, the uterus will begin to descend, and 1-2 weeks before delivery, the fetus's head will mostly have descended into the pelvis. Therefore, the uterine height can also roughly determine whether the fetus has entered the pelvis and estimate the approximate due date.