The fetus is slowly growing in your belly, from a tiny one to a big one, and its weight is increasing. During pregnancy checkups at the hospital, the doctor will tell you how your baby is developing, but what if the pregnant mother wants to know how her baby is developing all the time?
How to calculate the weight of the fetus?
How to calculate the weight of the fetus? During the first three months of pregnancy, the fetal length (centimeters) is calculated by measuring the distance from the head to the buttocks of the fetus.
As the fetus develops, the fetal head circumference or the diameter between the parietal bones, the abdominal circumference and the length of the thigh bones are measured from the 15th week of gestation to determine the size of the fetus, and then the fetal weight is estimated from these measurements (metric
This is used to estimate the fetal weight (grams). Because of the large error in measuring fetal length, for example, the curled position of the fetus and the size of the skeleton may cause misjudgment of the result, therefore, weight rather than length is used as the basis for assessing fetal growth in medical practice.
The specific public announcement is as follows.
Fetal weight calculation formula I: Fetal weight (g) = -4973.72 + 260.69*HC (head circumference)
Fetal weight calculation formula II: Fetal weight (g) = -2686.60 + 171.48*AC (abdominal circumference)
Fetal weight calculation formula III: Fetal weight (g) = -2232.56 + 747.42*FL (femur length)
Fetal weight formula IV: Fetal weight (g) = -2513.51 + 1049.90*FTH (fetal subcutaneous fat thickness of the legs)
Fetal weight formula V: Fetal weight (g) = -5168.32 + 100.97*HC (head circumference) + 110.86*AC (abdominal circumference) +
143.09*FL(femur length) + 331.43*FTH(fetal subcutaneous fat thickness of the legs)
Fetal weight formula 6: Fetal weight (g) = 900*BPD (biparietal diameter) – 5200
Fetal weight formula 7: Fetal weight (g) = 2900 + 0.3*Fetal height*Waist circumference
Note: The above formula is only an estimate of fetal weight and does not represent the actual weight of the baby at birth. The purpose of predicting fetal weight is to detect any problems in fetal development at an early stage. Generally speaking, the actual birth weight is different from the predicted birth weight.
In general, the actual birth weight and the predicted birth weight have an error of plus or minus 10-15%. For example, if the birth weight is 4000 grams, the margin of error will be 400 grams. In other words, the larger the baby’s weight, the larger the margin of error.
The three main parameters for calculating fetal weight
1.Biparietal diameter (BPD)
BPD is not the circumference of the head, but the length of the parietal diameter on both sides of the bone, which is located near the temple; abdominal circumference is measured in the same plane where the liver and stomach of the fetus are located; and the thigh bone is shaped like a bone that puppies love to eat on ultrasound, which the mother-to-be can observe carefully through the ultrasound display screen.
2. Abdominal Circumference (AC)
Some doctors also measure the abdominal circumference of the mother: the highest part of the abdomen is measured horizontally, but because the abdominal circumference of each mother-to-be varies greatly, it is recommended that mothers-to-be measure themselves regularly at home.
3. Femoral length (FL)
The length from the base of the mother’s uterus (near the bottom of the mother’s sternum) to the upper edge of the pubic symphysis is measured by the physician in a supine position in order to estimate the growth of the fetus, which usually corresponds to this distance at 20 weeks of pregnancy or more.