Precise fetal calculation formula

Before the baby is born, the doctor can know the baby's weight. At this point, everyone must be curious about how the doctor evaluates the fetal weight calculation formula? In fact, the fetal weight calculation formula only predicts the fetal weight. Generally, the actual weight of a newborn at birth is plus or minus 10-15% away from the predicted weight.

Formula for calculating fetal weight

The purpose of predicting fetal weight is to detect problems in the baby's development as early as possible. Generally speaking, the actual weight at birth is also within 10-15% of the predicted weight. For example, if the birth weight is 4000 grams, the deviation range will be 400 grams. In other words, the larger the newborn's weight, the greater the deviation range.

In fact, when pregnant women go to the hospital for a physical examination, you can immediately ask the B-ultrasound doctor or obstetrician and gynecologist, who will tell you the weight of the fetus.

The following calculation method is only an estimate of fetal weight and does not mean the specific weight of the baby when it is born.

Fetal weight calculation method 1

Fetal weight (g) = -4973.72 260.69*HC (baby head circumference)

Fetal weight calculation method 2

Fetal weight (g) = -2686.60 171.48*AC (fetal abdominal circumference)

Fetal weight calculation method 3

Fetal weight (g) = -2232.56 747.42*FL (femur length)

Fetal weight calculation method 4

Fetal weight (g) = -2513.51 1049.90*FTH (fetal foot fat thickness)

Method 5 for calculating fetal weight

Fetal weight (g) = -5168.32 100.97*HC (baby head circumference) 110.86*AC (fetal abdominal circumference) 143.09*FL (femur length) 331.43*FTH (fetal foot fat thickness)

Fetal weight calculation method 6

Fetal weight (g) = 900*BPD (biparietal diameter) - 5200

Fetal weight calculation method seven

Fetal weight (g) = 2900 0.3* uterine fundus height* hip circumference

Calculate the baby's weight formula

The principle of the fetal weight calculator is based on the calculation based on ultrasound measurement. It uses Shepard's formula to calculate (biparietal diameter x abdominal circunference) and displays the results of LB and KG.

Method 1

Formula calculation 1: Y = -4973.72 260.69HC

Formula calculation 2: Y = -2686.60 171.48AC

Formula calculation 3: Y = -2232.56 747.42FL

Formula calculation 4: Y = -2513.51 1049.90FTH

Formula calculation 5: Y = -5168.32 100.97HC 110.86AC 143.09FL 331.43FTH

The main parameters can be found from the B-ultrasound report:

Y: estimated fetal weight (g), HC: baby's head circumference, AC: fetal abdominal circumference, FL: femur length, FTH: fetal foot fat thickness

Method 2

Fetal weight is proportional to the number of weeks:

Preset resting weight (EBW) = the ratio of biparietal diameter to periodontal biparietal diameter (BPD) / the ratio of fetal abdominal circumference to periodontal fetal abdominal circumference (AC) / the ratio of femur length to periodontal femur length (FL) ±15% error.

However, it is not possible to group all pregnant women of different gestational ages around the world together, so nowadays, in order to estimate the weight of the baby in the belly, statistical methods are used to measure it accurately.