Combination of Fundal Height and Ultrasound to Predict Small for Gestational Age at Birth

Katherine L. Grantz*, Ana M. Ortega-Villa, Sarah J. Pugh, Alaina Bever, William Grobman, Roger B. Newman, John Owen, Deborah A. Wing, Paul S. Albert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Objective: The objective of the study was to determine whether adding longitudinal measures of fundal height (FH) to the standard cross-sectional FH to trigger third trimester ultrasound estimated fetal weight (EFW) would improve small for gestational age (SGA) prediction. Study Design: We developed a longitudinal FH calculator in a secondary analysis of a prospective cohort study of 1,939 nonobese pregnant women who underwent serial FH evaluations at 12 U.S. clinical sites. We evaluated cross-sectional FH measurement ≤ -3 cm at visit 3 (mean: 32.0±1.6 weeks) versus the addition of longitudinal FH up to and including visit 3 to trigger an ultrasound to diagnose SGA defined as birth weight <10th percentile. If the FH cut points were not met, the SGA screen was classified as negative. If FH cut points weremet and EFWwas <10th percentile, the SGA screen was considered positive. If EFW was ≥10th percentile, the SGA screen was also considered negative. Sensitivity, specificity, and positive predictive value (PPV) and negative predictive value (NPV) were computed. Results: In a comparison of methods, 5.8% of women were classified as at risk of SGA by both cross-sectional and longitudinal classification methods; cross-sectional FH identified an additional 4.0%, and longitudinal fundal height identified a separate, additional 4.5%. Using cross-sectional FH as an ultrasound trigger, EFWhad a PPV and NPV for SGA of 69 and 92%, respectively. After adding longitudinal FH, PPV increased to 74%, whereas NPV of 92% remained unchanged; however, the number of women who underwent triggered EFW decreased from 9.7 to 5.7%. Conclusion An innovative approach for calculating longitudinal FH to the standard cross-sectional FH improved identification of SGA birth weight, while simultaneously reducing the number of triggered ultrasounds. As an essentially free-of-charge screening test, our novel method has potential to decrease costs as well as perinatal morbidity and mortality (through better prediction of SGA).

Original languageEnglish (US)
Pages (from-to)155-162
Number of pages8
JournalAmerican journal of perinatology
Volume40
Issue number2
DOIs
StatePublished - Jan 1 2023

Keywords

  • birth weight percentile
  • fundal height
  • small for gestational age

ASJC Scopus subject areas

  • Obstetrics and Gynecology
  • Pediatrics, Perinatology, and Child Health

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