Work

Impact of fetal and maternal characteristics on the accuracy and precision of sonographic fetal weight estimation: population‐based study

Year: 2025

Type: article

Abstract: OBJECTIVE: Ultrasound-based fetal growth assessment is an essential part of clinical decision-making in modern obstetric care. This study aimed to evaluate the impact of maternal and fetal characteristics on the accuracy and precision of sonographic fetal weight estimation. METHODS: We included 31 521 singleton pregnancies registered in the Swedish Pregnancy Register between January 2014 and December 2021, with delivery ≥ 22 + 0 weeks' gestation and estimated fetal weight (EFW) assessed using ultrasound within 2 days before delivery. Fetal biometric ultrasound measurements were used to calculate EFW according to the formula of Persson and Weldner. Mean percentage error (MPE) and the proportion of EFW within ± 10% of the birth weight were calculated and stratified by maternal body mass index (BMI), fetal sex, fetal presentation at birth, gestational age (GA) at ultrasound and standardized EFW (estimated small-for-gestational age (SGA), appropriate-for-gestational age (AGA) or large-for-gestational age). Univariable and adjusted risk ratios (aRRs) for poor EFW assessment, defined as EFW deviating more than ± 10% from the birth weight, were calculated. RESULTS: percentile) across all subgroups of GA at ultrasound (overall MPE, -5.4 ± 9.8%; 67% of estimates within ± 10% of birth weight). The risk of poor fetal weight estimation was highest for severe-SGA-estimated vs AGA-estimated fetuses (aRR, 1.44 (95% CI, 1.38-1.51)). Additionally, the risk of poor fetal weight estimation was higher for male vs female fetuses (aRR, 1.09 (95% CI, 1.05-1.14)), non-cephalic vs cephalic presentation (aRR, 1.20 (95% CI, 1.13-1.28)) and preterm vs late term (39 + 0 to 40 + 6 weeks) GA at ultrasound, with the highest risk observed for those with GA of 22 + 0 to 27 + 6 weeks at ultrasound (aRR, 1.30 (95% CI, 1.13-1.50)). CONCLUSIONS: All assessed fetal characteristics, especially standardized EFW, affected the accuracy of ultrasonographic fetal weight estimation. Understanding systematic errors in the EFW formula used is of utmost importance in clinical decision-making to prevent unnecessary or missed obstetric interventions. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Source: Ultrasound in Obstetrics and Gynecology

DOI: 10.1002/uog.70117

Authors: M. Granfors, Ä. Mantel, O. Axelsson, S. Cnattingius, L. Lindström

Institutions: Karolinska University Hospital, Karolinska Institutet, Uppsala University

Language: English

Topic: Pregnancy and preeclampsia studies

Subfield: Obstetrics and Gynecology

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $4,940