Personalized third-trimester fetal growth evaluation: comparisons of individualized growth assessment, percentile line and conditional probability methods

Abstract

Objective To compare third trimester size trajectory prediction errors for three individualized fetal growth assessment methods. Methods This study utilized longitudinal measurements of 9 directly measured size parameters in 118 fetuses with normal neonatal growth outcomes. Expected Value [EV] function coefficients and variance components were obtained using two-level random coefficient modeling. Growth models [IGA] or EV coefficients and variance components [PLM, CPM] were used to calculate predicted values at approximately 400 3rd trimester time points. Percent Deviations [% Dev] calculated at these time points were expressed as percentages of their IGA, age-specific reference ranges (T%Dev). Third trimester T%Dev values were averaged [aT%Dev] for each parameter. Means ± SD’s for sets of aT%Dev values derived from each method [IGA, PLM, CPM] were calculated and compared. Results Mean aT%Dev values for nine parameters were: 1) IGA: – 4.3 to 5.2% [9/9 not different from zero]; 2) PLM: −32.7% to 25.6% [4/9 not different from zero]; and 3) CPM: −20.4% to 17.4% [5/9 not different from zero]. Seven of nine systematic deviations from zero were statistically significant when IGA values were compared to either PLM or CPM values. Variabilities were smaller for IGA when compared to those for PLM or CPM, with 1) 5/9 being statistically significant [IGA vs. PLM], 2) 2/9 being statistically significant [IGA vs. CPM] and 3) 5/9 being statistically significant [PLM vs. CPM]. Conclusions Significant differences in the agreement between predicted third trimester size parameters and their measured values were found for the three methods tested. With most parameters, IGA gave smaller mean aT%Dev values and smaller variabilities. The CPM method was better than PLM approach for most but not all parameters. These results suggest that 3rd trimester size trajectories are best characterized by IGA in fetuses with normal growth outcomes.

Fractional fetal thigh volume in the prediction of normal and abnormal fetal growth during the third trimester of pregnancy

“…These velocity values were then compared to reference ranges previously calculated in a cohort of fetuses with normal growth outcomes. 28 Participants (n = 0) delivering before their 34- to 36-week scan were excluded. Expected and observed measurements at 34-36 weeks were compared as follows: percent deviation = 100 × (observed-predicted)/predicted.…”

“… 23 , 24 , 25 , 26 Second-trimester TVol measurements can also be used to generate Rossavik models for predicting TVol and EFW growth trajectories during the third trimester. 27 , 28 …”

The usefulness of fetal Doppler evaluation in early versus late onset intrauterine growth restriction. Review of the literature.

“…The diagnosis of L-IUGR is more difficult, due to the large variability of fetal parameters on growth charts in the third trimester [4,31]. L-IUGR can be suspected when the individual growth curve slows down or even become flat [32] (fig 4).…”

Intraexaminer and Interexaminer Variability in 3D Fetal Volume Measurements During the Second and Third Trimesters of Pregnancy

“…There is also the potential for using 3D sonography to measure fetal volumes at earlier gestations to enable calculation of ideal third‐trimester growth trajectories . This particular use of 3D sonography, using the fractional thigh volume and Rossavik growth models in individualized growth assessment, has been prospectively evaluated in a normal‐pregnancy population and showed good prediction of third‐trimester growth from second‐trimester measurements . Other studies examining placental volumes in the first‐trimester have demonstrated that 3D methods are superior when compared to 2D sonography with regard to the accuracy of volume measurements .…”

“…5 This particular use of 3D sonography, using the fractional thigh volume and Rossavik growth models in individualized growth assessment, has been prospectively evaluated in a normal-pregnancy population and showed good prediction of thirdtrimester growth from second-trimester measurements. 6,7 Other studies examining placental volumes in the first-trimester have demonstrated that 3D methods are superior when compared to 2D sonography with regard to the accuracy of volume measurements. 8 Placental volumes have been evaluated in an attempt to enable earlier detection of those pregnancies resulting in small-for-gestational-age neonates, early-onset intrauterine growth restriction, and preeclampsia.…”