Fetal weight: growth charts

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The weight of the fetus is used to evaluate its correct development

With ultrasound it is possible "take measurements "of the fetus (length, circumference, etc.) and from these measurements the theoretical weight of the fetus, which is one of the parameters to evaluate its correct development. The measurements obtained with the ultrasound are then compared with the statistical tables to see if they fall within the indicated parameters or not.


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In this article

  • How is the weight of the fetus determined? 
  • The growth charts of the fetus 
  • Female fetal weight by week of pregnancy
  • Male fetal weight by week of pregnancy
Read also: Fetal weight: how it is calculated and why it is an important parameter

How is the weight of the fetus determined?

Il weight of a fetus to be compared with the percentile table obviously cannot be measured, but it does come calculated from other sizes (abdominal circumference and biparietal diameter).

During the ultrasound scans, the gynecologist detects many values ​​of the baby, which are generally indicated with abbreviations and which are used to evaluate the fetal size and the growth rate per week of gestation:

  • AC (abdominal circumference)
  • BDP (biparietal diameter)
  • HC (head circumference)
  • HL (humerus length)
  • FL/FE/F (femur length)
  • ODP (occipito-frontal diameter)

The weight is assumed

It must be remembered that the fetal weight identified by the ultrasound is always alleged, «This means that it is never 100% correct, but that it has a margin of error of 10% more or less. The child, therefore, could weigh up to 10% more or less than the data obtained from the ultrasound ".

Read also: The development of the fetus in the 40 weeks

The growth charts of the fetus

There are tables that allow you to follow the progress of the fetal growth during pregnancy. 
Le measurements on the fetus are detected through theechography and are then compared with the "standard" tables allow to find some health problems of the child. That is why the ultrasound and the correct interpretation of the measurements of the fetus they are very important.

One of the main global challenges ofWHO (World Health Organization) is decrease the mortality and perinatal morbidity. Early diagnosis of the problems that may arise during pregnancy or the first months of life is essential to intervene quickly and effectively and ultrasound scans and weight estimates during pregnancy are essential for identifying and managing high-risk pregnancies. 

WHO has asked for the drafting of fetal growth charts based on multiple populations, and not as it was in the past relying on individual populations of some high-income countries. These tables are available for general use and provide a basis for preventing certain diseases and promoting one healthy lifestyle even before birth.

Read also: Fetal growth retardation: what it is, how to intervene, what are the prospects for the future

Female fetal weight by week of pregnancy

Fonte: doi10.1371/journal.pmed1002220.t011

Male fetal weight by week of pregnancy

Fonte: doi10.1371/journal.pmed1002220.t011
Read also: Fetal macrosomia: what to do if the fetus is large

Questions and answers

When is the fetal weight calculated?   

Until the 12th week of gestation, we only measure the length of the fetus, considering the distance from the head to the butt of the baby (CRL). Subsequently, it is possible to obtain an estimate of the weight automatically thanks to the sophisticated ultrasound machines in use today.

How and how much does the fetal weight increase?  

The weight of the fetus increases by about 100 grams per week until the 30th week; after that it grows even faster. 

  • development of the fetus
  • fetal growth
  • fetus size
  • growth tables
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