pregnant woman with ultrasound image

Measuring the weight of the fetus is an important part of keeping both mother and baby safe, since a clinically high birth weight is a risk factor for pregnancy-related complications.

A recent study investigated 3D limb volume together with abdominal circumference to create a measurement that would be able to predict fetal weight. According to the authors, current methods to predict fetal weight can vary in accuracy, and have some limitations.

For the study, the researchers collected ultrasound images using a colour Doppler ultrasound diagnostic instrument. The researchers collected 3D and 2D images, and measured the arm volume, thigh volume, and abdominal circumference of the fetus.

Using the measurements, the researchers were able to create an algorithm to predict birthweight. This new algorithm was tested for accuracy and compared with existing methods of predicting birthweight.

The new algorithm was shown to predict birthweight well, and even better than some of the currently used methods. The researchers reported that greater fetal arm volume, thigh volume, and abdominal circumference was associated with higher weights at birth. The new algorithm was able to predict high birth weight in 87.5% of cases.

According to the researchers, fetal limb volumes will likely become a measurement used to predict fetal weight in the future.


Kang, Li; Wu, Qing-Qing; Sun, Li-Juan; Gao, Feng-Yun; Wang, Jing-Jing Predicting fetal weight by three-dimensional limb volume ultrasound (AVol/TVol) and abdominal circumference, Chinese Medical Journal: May 5, 2021 – Volume 134 – Issue 9 – p 1070-1078 doi: 10.1097/CM9.0000000000001413

News release: Ultrasonic method improves accuracy of fetal weight prediction during pregnancy

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