A new formula for optimized weight estimation in extreme fetal macrosomia (≥4500 g)

F Faschingbauer; U Dammer; J Siemer; R Schild; M Schmid; MW Beckmann; S Kehl

doi:10.1055/s-0033-1355065

Ultraschall in der Medizin - European Journal of Ultrasound, Inhaltsverzeichnis

A new formula for optimized weight estimation in extreme fetal macrosomia (≥4500 g)

F Faschingbauer ¹, U Dammer ¹, J Siemer ², R Schild ³, M Schmid ⁴, MW Beckmann ¹, S Kehl ¹

¹Universitätsfrauenklinik Erlangen, Erlangen, Germany
²Ludmillenstift Meppen, Department of Obstetrics and Perinatal Medicine, Meppen, Germany
³DDH Frauenkliniken, Department of Obstetrics and Perinatal Medicine, Hanover, Germany
⁴Universität Erlangen, Department of Medical Informatics, Erlangen, Germany

Abstract

Purpose: To develop and to evaluate a specific sonographic weight formula for fetuses with extreme macrosomia (≥4500 g).

Material and methods: A statistical estimation technique known as “gradient boosting with component-wise P-splines” was applied to a group of 174 fetuses with a birth weight (BW) ≥4500 g. Each fetus underwent an ultrasound examination with complete biometric parameters within 7 days of delivery. Exclusion criteria were multiple pregnancy, intrauterine death, and major structural or chromosomal anomalies. A new formula was derived using the data obtained and was then compared with currently available equations for estimating weight in the macrosomic fetus.

Results: The new formula derived is: log₁₀ (EFW)= 3.6687781710 – 0.0003230278 * (BPD – 100.4080) – 0.0000843433 * (BPD – 100.4080)² + 0.0007281281 * (OFD – 120.6322) + 0.0000664323 * (OFD – 120.6322)² + 0.000000001794019 * exp(ATD – 120.1552) + 0.0005946974 * (APAD – 121.2069) – 0.0000210137 * (APAD – 121.2069)² – 0.000003318 * (APAD – 121.2069)³, where EFW is estimated fetal weight, BPD is biparietal diameter, OFD is occipitofrontal diameter, ATD is abdominal transverse diameter, and APAD is abdominal anteroposterior diameter. The new formula proved to be superior to other established equations, showing the lowest mean absolute percentage error (MAE 2.506), the smallest variance regarding the signed percentage error (SPE) (SD: 3.376), and the best distribution of absolute percentage errors within prespecified error bounds.

Conclusion: This new formula significantly improves weight estimation in the fetus with extreme macrosomia.