Predicting term birth weight using ultrasound and maternal characteristics

Area of Science:

• Obstetrics and Gynecology
• Medical Imaging
• Biostatistics

Background:

• Accurate estimation of fetal weight (EFW) is crucial for managing high-risk pregnancies and optimizing delivery timing.
• Existing ultrasound-based prediction formulas, such as those by Hadlock, Shepard, and Nahum, have varying degrees of accuracy.
• Maternal characteristics can influence fetal growth and may improve EFW prediction.

Purpose of the Study:

• To develop and validate a new ultrasound-based equation for estimating fetal weight (EFW) using maternal characteristics.
• To compare the accuracy of the new Halaska equation against established formulas by Hadlock, Shepard, and Nahum.
• To assess the performance of different equations in predicting birth weight across various fetal sizes.

Main Methods:

• Two groups of healthy term pregnant women were recruited (Group A: 125, Group B: 130).
• Standard ultrasonographic measurements (BPD, AC, FL) and maternal characteristics were recorded.
• A new EFW equation was derived using multiple stepwise regression analysis on Group A data and validated on Group B data against existing formulas.

Main Results:

• The new Halaska equation is: log(10) EFW=0.64041xBPD-0.03257xBPD(2)+0.00154xACxFL.
• The Halaska and Hadlock equations demonstrated comparable accuracy and were superior to Shepard and Nahum equations.
• The Halaska equation showed the highest overall accuracy, while Hadlock's formula performed better for fetuses over 4000g, requiring further validation.

Conclusions:

• The newly developed Halaska ultrasound-based equation provides accurate fetal weight estimations, comparable to the Hadlock formula.
• Both Halaska and Hadlock equations are recommended for clinical use over Shepard and Nahum formulas.
• The Nahum equation offers a simple, inexpensive, and approximate estimation method.