Comparing Fetal Ultrasound Biometric Measurements to Neonatal Anthropometry at the Extremes of Birthweight

Jessica L Gleason; Mary L Hediger; Zhen Chen; Jagteshwar Grewal; Roger Newman; William A Grobman; John Owen; Katherine L Grantz

doi:10.1055/a-2298-5245

Comparing Fetal Ultrasound Biometric Measurements to Neonatal Anthropometry at the Extremes of Birthweight

Am J Perinatol. 2024 May 10. doi: 10.1055/a-2298-5245. Online ahead of print.

Authors

Jessica L Gleason¹, Mary L Hediger¹, Zhen Chen², Jagteshwar Grewal³, Roger Newman⁴, William A Grobman⁵, John Owen⁶, Katherine L Grantz¹

Affiliations

¹ Division of Population Health Research, Division of Intramural Research, Epidemiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.
² Division of Population Health Research, Division of Intramural Research, Biostatistics and Bioinformatics Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.
³ Division of Population Health Research, Division of Intramural Research, Office of the Director, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.
⁴ Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina.
⁵ Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio.
⁶ Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama.

PMID: 38569506
DOI: 10.1055/a-2298-5245

Abstract

Objective: Error in birthweight prediction by sonographic estimated fetal weight (EFW) has clinical implications, such as avoidable cesarean or misclassification of fetal risk in labor. We aimed to evaluate optimal timing of ultrasound and which fetal measurements contribute to error in fetal ultrasound estimations of birth size at the extremes of birthweight.

Study design: We compared differences in head circumference (HC), abdominal circumference (AC), femur length, and EFW between ultrasound and corresponding birth measurements within 14 (n = 1,290) and 7 (n = 617) days of birth for small- (SGA, <10^th percentile), appropriate- (AGA, 10^th-90^th), and large-for-gestational age (LGA, >90^th) newborns.

Results: Average differences between EFW and birthweight for SGA neonates were: -40.2 g (confidence interval [CI]: -82.1, 1.6) at 14 days versus 13.6 g (CI: -52.4, 79.7) at 7 days; for AGA, -122.4 g (-139.6, -105.1) at 14 days versus -27.2 g (-50.4, -4.0) at 7 days; and for LGA, -242.8 g (-306.5, -179.1) at 14 days versus -72.1 g (-152.0, 7.9) at 7 days. Differences between fetal and neonatal HC were larger at 14 versus 7 days, and similar to patterns for EFW and birthweight, differences were the largest for LGA at both intervals. In contrast, differences between fetal and neonatal AC were larger at 7 versus 14 days, suggesting larger error in AC estimation closer to birth.

Conclusion: Using a standardized ultrasound protocol, SGA neonates had ultrasound measurements closer to actual birth measurements compared with AGA or LGA neonates. LGA neonates had the largest differences between fetal and neonatal size, with measurements 14 days from delivery showing 3- to 4-fold greater differences from birthweight. Differences in EFW and birthweight may not be explained by a single fetal measurement; whether estimation may be improved by incorporation of other knowable factors should be evaluated in future research.

Key points: · Ultrasound measurements may be inadequate to predict neonatal size at birth.. · Birthweight estimation error is higher for neonates >90th percentile.. · There is higher error in AC closer to birth..

Grants and funding

HHSN275200800013C; HHSN275200800002I; HHSN27500006/NH/NIH HHS/United States