How to estimate fetal weight formula

During pregnancy, pregnant mothers will always pay attention to the development of the fetus. By understanding the weight of the fetus, pregnant mothers can understand whether the fetus is growing and developing healthily. There are many medical formulas for estimating the baby's weight. For example, the weight of the fetus can be calculated based on the data from the B-ultrasound during the prenatal examination. So how to estimate the baby's weight and what is the formula? Come on and move forward!

How to estimate baby's weight formula

Predictive analysis of baby weight calculation formula 1: baby weight (g) = -4973.72 260.69*HC (baby head circumference)

Predictive analysis of baby weight calculation formula 2: baby weight (g) = -2686.60 171.48*AC (fetal abdominal circumference)

Predictive analysis of baby weight calculation formula three: baby weight (g) = -2232.56 747.42*FL (fetal femur length)

Predict baby weight calculation formula 4: baby weight (g) = -2513.51 1049.90*FTH (fetal foot fat thickness)

Predict baby weight calculation formula 5: baby weight (g) = -5168.32 100.97*HC (baby head circumference) 110.86*AC (fetal abdominal circumference) 143.09*FL (fetal femur length) 331.43*FTH (fetal foot fat thickness)

Predictive analysis of baby weight calculation formula six: baby weight (g) = 900*BPD (fetal biparietal diameter) - 5200

Predictive analysis of baby weight calculation formula seven: baby weight (g) = 2900 0.3 * uterine fundus height * chest size

Should the baby's weight standard be compared with that of babies of the same gestational age?

Is the fetal weight normal? What are the indicators? Who are you comparing with?

The weight of the baby in the mother's belly is compared with that of the fetus of the same week. Assuming that a pregnant woman is 28 weeks pregnant, if she wants to know whether the weight of her newborn is normal, she needs to combine the pregnant women who are also 28 weeks pregnant, calculate the average weight of the babies in this group of pregnant women, and then check how far this pregnant woman is from this average. Therefore, different weeks of pregnancy will produce different averages.

Three factors that affect the estimation of baby's weight

Doctors usually use B-ultrasound to estimate the weight of the fetus, and then compare the results with previous statistical data (gestational age and weight estimation table). Because the database used for comparison is different, the posture of the fetus, congenital genetic factors, and the accuracy of the B-ultrasound equipment used will affect the doctor's judgment on the baby's weight. Therefore, even if you go to different medical institutions for prenatal check-ups on the same day, the measured baby weight will not be exactly the same.

Factor 1: Baby weight development curve chart

Needless to say, you don't know, in fact, the fetus also has a weight growth curve, which is a reference commonly used by hospitals to assess the gestational age and weight growth of the fetus. This growth curve is the result of analysis based on hundreds of thousands of baby weight data in the past. The doctor will check the growth status of the fetus based on this data to determine which growth range the fetus's weight falls into. If the fetus's weight falls below 10% (too small) or above 90% (too large), there may be abnormal causes. Pay special attention and do further examinations to find the cause. The databases selected for reference by various medical research institutes come from different sources. For example, if the statistics of Western countries are used, the weight of Chinese fetuses at the same gestational week may be slightly lower, while if some Japanese statistics are used, the weight of Chinese fetuses may be higher. Even if the databases analyzed by various research centers in China are used, there are still significant gaps. Therefore, the results estimated by different medical research institutes will also vary. In addition, when the baby's weight falls within the growth range below 10% or above 90%, since there are very few fetuses with weight in this range, the data obtained are also very small, the error is relatively large, and it may not be very accurate.

Element 2: Practical operation methods and application instruments and equipment

B-ultrasound is a necessary special tool for accurately measuring the baby's weight, so the accuracy of the instrument will also affect the judgment result. In addition, the doctor's actual method of operating the instrument will also have some impact on the accurate measurement results.

Factor 3: Fetal posture and congenital factors

Whether it is to accurately measure the body length or the baby's head circumference, fetal abdominal circumference and thigh bone length, the baby's posture will affect the accurate measurement results. Because the growth of the fetus is assessed by measuring the baby's head circumference, abdominal circumference and thigh bone length, if the fetus is fat or tall, the estimated error of its weight will be higher than that of an ordinary baby.