2074928 Determining Fetal Adiposity in Utero Based on Sonographic Measurements of Fetal Buoyancy (Rate of Fetal Rise, RFR)

Abstract

Accurate identification of pathologically large for gestational age (LGA) or small for gestational age (SGA) fetuses is clinically challenging; sonographic measurements tend to overestimate and underestimate the weights of suspected LGA and SGA fetuses, respectively. We sought to validate a new method for evaluating fetal weight in three groups of gravidae: those with an uncomplicated pregnancy, and those with suspected LGA or SGA. 34 gravidae with gestational age over 34 weeks were prosepectively enrolled. Routine biometry was performed and two sets of subcutaneous skin thickness were sonographically measured, alongside AFI and placental location and thickness. The fetus was then manually depressed downward and its ascent (rate of fetal rise (RFR)) was recorded in a clip. The rate of fetal rise was then calculated as a measure of frames, distance, and time. Postnatal anthropometry was completed, including PeaPod DEXA scanning in a subset of infants (n 10). Robustness of sonographic measurements to postnatal anthropometric measures were assessed by Pearson's, with linear regression for covariates. As shown in the table, there was no correlation between the RFR and infant birthweight. However, there were significant correlations between RFR and the neonate's BMI, Ponderal Index, and body fat percentage. Only 95% of sonographic measurements are within 20% of birthweight. Fetal buoyancy, as measured by the RFR, is a potentially promising new modality for predicting not only birthweight but also clinically relevant adiposity in the neonate.Tabled 1Pearson's correlation coefficients for rate of fetal rise against measures of neonatal adiposityMeasure of adiposityPearson's correlationSignificanceBody mass index0.3560.049Ponderal index0.3630.045Birth weight0.2820.124Fat mass0.3070.099Lean mass0.3380.067Body fat (%)0.3690.041 Open table in a new tab