Establish a new equation for ultrasonographic estimated fetal weight in Chongqing: a prospective study

Abstract Background: Variation in fetal growth between populations should not be ignored, and a single universal standard is not appropriate for everyone. Therefore, according to regional population characteristics, it is necessary to find a more accurate equation for ultrasound estimation of fetal weight. The purpose of this study was to create a new equation for ultrasound estimation of fetal weight according to the local population in Chongqing and compare it with representative equations. Methods: This prospective study included data on pregnant women who gave birth to a single child at full term in our hospital from December 2016 to November 2019. The fetal weight compensation model was established by using the second-order linear regression model, then the equation of fetal weight was established by utilizing the multiple reverse elimination regression technique. The accuracy of the equation established in this study was respectively compared with the Hadlock equation, Combs equation and Stirnemann equation by estimation error.Results: Through the fetal weight compensation equation, the predicted fetal weight equation suitable for Chongqing fetuses was successfully established with the variables of biparietal diameter, head circumference, abdominal circumference and femur length. In the sets established by 1925 data, the mean absolute error and standard deviation of the estimation error of the equation established in this study were 178.9g and 140.3g respectively. In the 300 validation sets, the mean absolute error and Standard deviation of Chongqing equation were 173.08g and 128.59g respectively. Compared with representative equations, the mean absolute error and the standard deviation of the new equation were the lowest.Conclusions: According to the local population characteristics of Chongqing, this study created the equation for estimated fetal weight, which is more accurate and suitable. This equation has high clinical guidance and reference value for monitoring and management of fetal weight and maternal delivery process.