Individualized Growth Assessment Research Articles

Can growth in dichorionic twins be monitored with individualized growth assessment?

To characterize fetal growth in dichorionic twins using individualized growth assessment (IGA), a method based on individual growth potential estimates. This secondary analysis included 286 fetuses/neonates from 143 dichorionic twin pregnancies that were part of the ESPRiT (Evaluation of Sonographic Predictors of Restricted Growth in Twins) study. The sample was subcategorized according to birth weight into appropriate-for-gestational-age (AGA) (n = 243) and small-for-gestational-age (SGA) (n = 43) cohorts. Serial biometric scans evaluating biparietal diameter, head circumference (HC), abdominal circumference, femur diaphysis length and estimated weight at 2-week intervals were used to evaluate fetal growth, while measurements of birth weight, crown-heel length and HC determined neonatal growth outcome. Six abnormalities (hypoxic ischemic encephalopathy, periventricular leukomalacia, necrotizing enterocolitis, respiratory distress, sepsis and death) constituted the evaluated adverse neonatal outcomes (ANO). IGA was used to: evaluate differences in second-trimester growth velocities between singletons (from a published dataset) and dichorionic twins (138 AGA twins with normal third-trimester growth); describe the degree to which actual third-trimester growth in twins followed expected growth (111 AGA twins, normal fetal growth and neonatal growth outcomes); determine if the fetal growth pathology score 1 (-FGPS1) could detect, quantify and classify twin growth pathology (224 AGA, 42 SGA); and assess the relationship between -FGPS1 and ANO (24 SGA twins with progressive growth restriction confirmed by abnormal neonatal growth outcome). The differences in second-trimester growth velocity between singletons and twins (means and variances) were small and not statistically significant. Percent deviations from the expected third-trimester size trajectories were within the 95% reference ranges derived from singletons at 95.7% (1677/1752) of timepoints studied. Abnormal growth was detected in 37.9% of AGA twins and 85.7% of SGA twins. Growth restriction was more heterogeneous in AGA twins, while in SGA twins progressive growth restriction was the principal type (66.7%). -FGPS1 patterns previously defined in singletons classified 97.5% of pathological twin cases. In our most severe form of growth restriction (progressive), there were only three (12.5%) ANOs related to growth abnormalities, all in cases with -FGPS1 values more negative than -2.0%. Using these criteria, the frequency of ANO was 33%. With respect to growth, dichorionic twins can be considered as two singletons in the same uterus. Normally growing dichorionic twins have the same growth potential as singletons with normal growth outcome. These twins also follow expected third-trimester growth trajectories with the same precision as do singletons. Third-trimester growth pathology can be detected, quantified and classified using -FGPS1 as in singletons. Limited evidence of a relationship between fetal growth abnormalities and adverse neonatal outcome was found. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Defining Body Mass Index Using Weight and Length for Gestational Age in the Growth Assessment of Preterm Infants at Birth.

The objectives of this study were to describe (1) body mass indexes (BMIs) using weight and length for gestational age (GA) classifications, and (2) the additional information BMI, as a measure of body proportionality, provides for preterm infant growth assessment and care plans at birth. Birth weight, length, and BMI of 188,646 preterm infants (24-36 weeks gestation) admitted to U.S. neonatal intensive care units (Pediatrix Clinical Data Warehouse, 2013-2018) were classified (Olsen curves) as small, appropriate, or large for GA (SGA < 10th, AGA 10-90th, LGA > 90th percentile for GA, respectively). The distribution for the 27 weight-length-BMI combinations was described. At birth, most infants were appropriate for weight (80.0%), length (82.2%), head circumference (82.9%), and BMI (79.9%) for GA. Birth weight for GA identified approximately 20% of infants as SGA or LGA. Infants born SGA (or LGA) for both weight and length ("proportionate" in size) were usually appropriate for BMI (59.0% and 75.6%). BMI distinguished disproportionate weight for length in infants with SGA or LGA weight at birth (58.3%, 49.9%). BMI also identified 11.4% of AGA weight infants as small or large for BMI ("disproportionate" in size) at birth; only using weight for GA missed these underweight/overweight for length infants. The unique, additional information provided by birth BMI further informs individualized preterm infant growth assessment by providing an assessment of an infant's body proportionality (weight relative to its length) in addition to the routine assessment of weight, length, and head circumference for GA and may better inform care plans and impact outcomes. · Most preterm infants were born AGA for all growth measures.. · AGA weight infants may be under- or overweight for length.. · BMI distinguished body disproportionality in SGA/LGA infants.. · Recommend BMI assessed along with weight, length and head.. · Further research on BMI in preterm infants is needed..

Second-trimester growth velocities in twin and singleton pregnancies.

Previous small studies used individualized growth assessment (IGA) to characterize prenatal growth velocities of singletons and twins. We aimed to compare second-trimester growth velocities of individual anatomical parameters between monochorionic diamniotic (MCDA) twins, dichorionic diamniotic (DCDA) twins and singleton fetuses in a larger study. This was a study of a novel cohort of 222 MCDA twins and previously published cohorts of 40 DCDA twins and 118 singletons with serial ultrasound data. Fetal biometric measurements of biparietal diameter, head circumference, abdominal circumference and femur diaphysis length from prenatal ultrasound examinations were used to calculate second-trimester growth velocities using direct calculation or linear regression analysis. Linear fit was assessed based on the coefficient of determination (R2 ). Mean growth velocities and variances were compared among the three groups. The majority of cases underwent three second-trimester ultrasound examinations with fetal biometry available. All fetuses had linear growth, with R2 > 99% for all parameters. Only 1-2% of all MCDA and DCDA anatomical parameters had abnormal growth velocity scores outside the 95% reference range for singletons. There were no significant differences in mean growth velocity for any parameter between MCDA twins and singletons. Femur diaphysis length growth velocity was significantly lower in DCDA twins than in both MCDA twins and singletons. There were no other significant differences among the groups. Expanding on prior work using IGA, we found that second-trimester growth velocity of the four major anatomical parameters overall was similar between twins and singletons and between MCDA and DCDA twins, supporting the use of singleton-derived growth standards for IGA in twins. Twin growth potential appears to be similar to that of singletons in the second trimester, suggesting that subsequent growth divergence may be due to third-trimester physiological or pathological changes in twin pregnancies. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Individualized growth assessment in pregnancies complicated by fetal gastroschisis

Objective Prenatal ultrasound (US) has been shown to overestimate the incidence of suspected fetal growth restriction (FGR) in gastroschisis cases. This is largely because of altered sonographic abdominal circumference (AC) measurements when comparing gastroschisis cases with population nomograms. Individualized Growth Assessment (IGA) evaluates fetal growth using serial US measurements that allow consideration of the growth potential for a given case. Our goal was to assess the utility of IGA for distinguishing normal and pathological fetal growth in gastroschisis cases. Study design Pregnancies with prenatally diagnosed fetal gastroschisis were managed and delivered at a single academic medical center. US fetal biometry including head circumference (HC), abdominal circumference (AC), and femur diaphysis length (FDL), and neonatal measurements including birthweight and HC were collected and analyzed for 32 consecutive fetal gastroschisis cases with at least two 2nd and two 3rd trimester measurements. Second trimester growth velocities were compared to a group of 118 non-anomalous fetuses with normal neonatal growth outcomes. Gastroschisis cases were classified into groups based on fetal growth pathology score (FGPS9) patterns. Agreement between IGA (FGPS9) and serial conventional estimated fetal weight (EFW) measurements for determining growth pathology was evaluated. Neonatal size outcomes were compared between conventional birthweight classifications for determining small for gestational age (SGA) and IGA Growth Potential Realization Index (GPRI) for weight and head circumference measurements. Results Fetal growth pathology score (FGPS9) measurements identified three in-utero growth patterns: no growth pathology, growth restriction and recovery, and progressive growth restriction. In the no growth pathology group (n = 19), there was 84% agreement between IGA and conventional methods in determining pathological growth in both the 3rd trimester and at birth. In the growth restriction and recovery group (n = 7), there was 71% agreement both in the 3rd trimester and at birth between IGA and conventional methods. In the progressive growth restriction group (n = 5), there was 100% agreement in the 3rd trimester and 60% agreement at birth between IGA and conventional methods. Conclusion We present the first study using IGA to evaluate normal and pathological fetal growth in prenatally diagnosed gastroschisis cases. IGA was able to delineate two 3rd trimester growth pathology patterns – one with persistent growth restriction and another with in-utero growth recovery. Further validation of these initial findings with larger cohorts is warranted.

Growth patterns and cardiovascular abnormalities in SGA fetuses: 3. Late, adaptive and recovering growth restriction

Objective To characterize abnormal growth processes and their associated cardiovascular abnormalities in SGA fetuses using Individualized Growth Assessment (IGA). Methods This longitudinal investigation utilized a SGA cohort [EFW and BW <10th percentile] derived from the PORTO study. Fetuses categorized by their Fetal Growth Pathology Score [FGPS1] patterns [Pattern 2 {n = 12}, Pattern 3 {n = 11}, Pattern 5 {n = 13}] were evaluated. Growth pathology was measured using the -FGPS1 and the individual composite Prenatal Growth Assessment Score {-icPGAS]. Paired cardiovascular assessments utilized measurements of the Pulsatility Index [umbilical artery {UA}, middle cerebral artery {MCA}, ductus venosus {DV}] and the myocardial performance index [MPI; heart]. Outcome variables were birth age [preterm or, term] and birth weight [small or normal (IGA criteria)]. Results Pattern 2 was usually characterized by a single, growth abnormality (67% of cases) of variable magnitude that occurred within two weeks of delivery {median onset age: 37.6 weeks}. The incidence of UA abnormalities was low (25%) while those of MCA and DV/MPI were high {60%, 42%}. Most neonates were of normal size (67%) and delivered at term (67%). Pattern 3 had an initial progressive growth restriction phase, followed by constant but abnormally low growth. Growth pathology had an early onset (median age: 31.6 weeks), was moderate but persistently abnormal. The incidences of cardiovascular abnormalities were moderate [30–50%]. Most neonates were abnormally small (80%) but delivered at term (90%). Pattern 5 had an initial progressive phase with an early onset [onset age {median}: 31.6 weeks]. However, this process was arrested and returned toward normal. Growth pathology magnitudes were minor as were the incidences of cardiovascular abnormalities. Neonatal size was usually normal and all fetuses delivered at term. Conclusions Characteristics of SGA Growth Restricted, Patterns 2, 3 and 5 are clearly different from those found in SGA Normal or SGA Growth Restricted Pattern 1 groups. They also differed from one another, indicating that growth restriction can manifest itself in several different ways. Pattern 2 is similar to “late” growth restriction reported previously. Patterns 3 and 5 are novel and have been designated as “adaptive” and “recovering” types of growth restriction.

Growth patterns and cardiovascular abnormalities in SGA fetuses: 2. Normal growth and progressive growth restriction

Objectives To characterize growth processes and their associated cardiovascular abnormalities in SGA fetuses with normal growth and progressive growth restriction patterns as defined by Individualized Growth Assessment (IGA). Methods A SGA cohort (EFW and BW < 10th percentile) was derived from the PORTO study that included 47 fetuses with normal growth outcome (SGA Normal) and 34 fetuses with progressive growth restriction (SGA Growth Restricted, Pattern 1). Composite fetal size parameters were used to quantify growth pathology at individual third trimester time points (individual composite Prenatal Growth Assessment Score {icPGAS}) and calculated cumulatively during the third trimester (Fetal Growth Pathology Score 1{FGPS1}). Paired Doppler evaluations of the umbilical artery (UA), middle cerebral artery (MCA), ductus venosus (DV) and myocardial performance index (MPI) were used to detect cardiovascular anomalies. Outcome variables were birth age and birth weight. Results Ranking fetuses with respect to the severity of the 3rd trimester growth pathology (–FGPS1) revealed three subgroups in each of these two groups. In SGA Normal, no (51%), minimal (19%) or minor (30%) growth abnormalities were present. Although vascular flow abnormalities occurred without growth abnormalities (UA: 38%; MCA: 35%), they increased with minor growth disturbances (UA: 64%; MCA: 50%). All fetuses delivered at term and in only 7 cases (minor growth abnormalities subgroup) were the neonates abnormally small based on IGA criteria. In SGA Growth Restricted, Pattern 1, the progression of growth restriction was slow (47%), moderate (21%) and rapid (32%). Corresponding median –FGPS1 values were −1.34%, −2.67% and −4.88%, respectively. The median age of onset was 33.6, 29.7 and 29.7 weeks in these three subgroups. UA abnormalities occurred infrequently in the first two subgroups but were found in all cases of rapidly progressing pathology. Similar results were found for the MCA and DV + MPI Doppler parameters (rapid progression: MCA = 50%; DV + MPI = 50%). Premature delivery occurred less frequently with slow progression but was nearly 100% in the moderately and rapidly progressive subgroups. Conclusions Negative FGPS1 growth restriction patterns can be used to classify SGA fetuses. Subgroups, based on ranked –FGPS1 values in both SGA Normal and SGA Growth Restricted Pattern 1 groups had marked differences in cardiovascular abnormalities and neonatal outcomes. The characteristics of these two groups are consistent with small, normally growing fetuses and fetuses with “early” growth restriction, respectively.

Growth patterns and cardiovascular abnormalities in small for gestational age fetuses: 1. Pattern characteristics

Background Fetal growth restriction is being defined as either “early” or “late” depending on age of onset. A recent investigation using individualized assessment has identified five different growth restriction patterns. No previous study has related these patterns to cardiovascular abnormalities. Objectives To determine growth patterns in small fetuses (BW < 10th percentile) using Individualized Growth Assessment (IGA) and to relate cardiovascular abnormalities found with Doppler ultrasound to these patterns. Study design A secondary analysis was carried out in 126 fetuses from the PORTO data set having both estimated weights and birth weights below the 10th percentile. Only fetuses with 2nd and 3rd trimester biometry scans appropriate for IGA and cardiovascular assessments were studied. There was one-to-one matching of biometry and Doppler evaluations in the 3rd trimester. Composite growth parameters were used to quantify growth pathology at individual time points (individual composite Prenatal Growth Assessment Score (icPGAS)) and during the 3rd trimester (Fetal Growth Pathology Score {FGPS1}). Normal and growth restriction patterns were identified using plots of FGPS1 values. Doppler measurements were classified as normal or abnormal based on published cross-sectional standards. Outcome variables were birth weight and birth age. Results In these SGA cases, 38.2% showed normal fetal growth and 61.8% had growth restriction. In the latter, seven different patterns were observed. Pattern 1 was most common (43.5%), followed by Patterns 5 (16.7%), 2 (15.4%) and 3 (14.1%). The characteristics of Pattern 1 indicated progressive growth restriction while Pattern 5 demonstrated recovery from an initial growth abnormality. Cardiovascular abnormalities were quite variable, with those in the umbilical artery being most frequent in Patterns 1 and 3. Pattern 2 had the highest incidence of middle cerebral artery abnormalities. Umbilical artery abnormalities were similar in the Normal and Pattern 5 groups as were those for the middle cerebral artery. Other cardiovascular abnormalities had low frequencies except in Pattern 2 where the ductus venosus incidence was high. Abnormally small neonates, as identified with IGA, were seen primarily in Patterns 1, 3 and 6 (80–88%). Premature deliveries occurred most frequently in Pattern 1 (56%), followed by Pattern 2 (33%). Conclusions Growth in this SGA Group was very heterogeneous with a significant proportion of these small fetuses growing normally. Growth restriction did not appear to be a single process but was manifest as seven different FGPS1 patterns. Both growth pathology and cardiovascular abnormalities differed among patterns. Further investigation will be required to determine how specific growth abnormalities are related to fetal cardiovascular changes over time.

Comparison of fetal size standards obtained with conventional methods and individualized assessment: the effect of adjusting for differences in growth potential

Objective: Detection of fetal growth restriction depends on the biometric standard definitions of normal variability. We examined the impact of correcting for differences in fetal growth potential on the variability of third-trimester size standards. Methods: Size standards, corrected differences in growth potential using Individualized Growth Assessment [IGA], were obtained in 119 pregnancies with normal neonatal growth outcomes. Using the same cohort, a second set of size standards, without these corrections, were determined with mixed modeling [IGA Cross-sectional]. An independent set of size standards, obtained by quantile regression in a population-based sample of 1387 pregnant women [World Health Organization (WHO)], was also evaluated. The anatomical parameters studied included BPD, HC, AC, FDL, THC, HDL, ArmC and EWT whenever possible. The variability measures compared were percent deviation reference range [IGA] or twice the coefficient of variation [IGA Cross-sectional, WHO] at weekly time points between 28 and 38 weeks, menstrual age. Results: All six IGA variabilities were significantly smaller [range: 19–60%] when IGA and IGA-cross-sectional size standards were compared. Similar IGA-WHO comparisons showed that the IGA variabilities for 5 of 6 anatomical parameters were significantly smaller [range: 26–32%; exception: FDL (5.8%)]. Comparisons of cross-sectional size standards gave variable results depending on the anatomical parameter studied. Conclusions: Third-trimester variability measures, based on IGA, were consistently lower than those obtained with conventional cross-sectional methods in normal pregnancies. These results were found when the identical sample was used in both IGA and cross-sectional analyses. Decreased variability can improve the sensitivity of IGA for detecting restricted growth and may be partly responsible for its ability to identify different types of growth abnormalities earlier in pregnancy.

193: Individualized Growth Assessment in pregnancies complicated by fetal gastroschisis

Fetal gastroschisis is associated with IUGR and SGA. Prenatal US may overcall IUGR because the abdominal circumference and associated weight estimations can be underestimated by herniated viscera. Individualized Growth Assessment (IGA) evaluates fetal and neonatal growth based on serial US measurements, thus is different from conventional methods that use population-based curves at fixed time points. Our goal was to assess the potential of IGA for separating normal and pathological growth in gastroschisis cases. Pregnancies with fetal gastroschisis that were managed and delivered at a single academic medical center were analyzed. Cases were classified into four groups by the presence of IUGR and SGA. IUGR was defined as US EFW <10th percentile by Hadlock formula; SGA was defined as birthweight <10th percentile by Fenton curve. Second and third trimester US fetal biometry and neonatal measurements were entered into iGAP software, which calculates fetal and neonatal growth pathology scores based on estimates of growth potential from 2nd trimester growth velocities. Agreement between conventional US methods and IGA was assessed. Of 70 pregnancies with fetal gastroschisis delivered between 2009 and 2016 at a single center, 21 pregnancies with at least four US measurements were included. In the no IUGR/no SGA group (n=12), there was 75% agreement (9/12) between IGA and conventional methods. IGA reported a negative prenatal growth score in three cases, but all showed a normal neonatal growth score. In the yes IUGR/yes SGA group (n=5) there was 100% agreement between IGA and conventional methods in assessing prenatal growth restriction. However, IGA reported a negative neonatal growth score in only two (40%) of the cases. In the yes IUGR/no SGA group (n=3), IGA resulted in a negative prenatal growth score in two (67%) cases, with a normal neonatal growth score in all three cases. In the one no IUGR/yes SGA case, IGA did not identify prenatal or neonatal growth pathology. We present the first study using IGA to evaluate pathological fetal and neonatal growth in gastroschisis cases. While we found general agreement between IGA and conventional US methods, IGA was able to identify normal growth and pathologic growth restriction missed by conventional methods in the prenatal and neonatal periods.

Individualized growth assessment: conceptual framework and practical implementation for the evaluation of fetal growth and neonatal growth outcome

Fetal growth abnormalities can pose significant consequences on perinatal morbidity and mortality of nonanomalous fetuses. The most widely accepted definition of fetal growth restriction is an estimated fetal weight less than the 10th percentile for gestational age according to population-based criteria. However, these criteria do not account for the growth potential of an individual fetus, nor do they effectively separate constitutionally small fetuses from ones that are malnourished. Furthermore, conventional approaches typically evaluate estimated fetal weight at a single time point, rather than using serial scans, to evaluate growth. This article provides a conceptual framework for the individualized growth assessment of a fetus/neonate based on measuring second-trimester growth velocity of fetal size parameters to estimate growth potential. These estimates specify size models that generate individualized third-trimester size trajectories and predict birth characteristics. Comparisons of measured and predicted values are used to separate normally growing fetuses from those with growth abnormalities. This can be accomplished with individual anatomical parameters or sets of parameters. A practical and freely available software (Individualized Growth Assessment Program) has been developed to allow implementation of this approach for clinical and research purposes.

Fetal growth velocity and body proportion in the assessment of growth.

Fetal growth restriction implies failure of a fetus to meet its growth potential and is associated with increased perinatal mortality and morbidity. Therefore, antenatal detection of fetal growth restriction is of major importance in an attempt to deliver improved clinical outcomes. The most commonly used approach towards screening for fetal growth restriction is by means of sonographic fetal weight estimation, to detect fetuses small for gestational age, defined by an estimated fetal weight <10th percentile for gestational age. However, the predictive accuracy of this approach is limited both by suboptimal detection rate (as it may overlook non-small-for-gestational-age growth-restricted fetuses) and by a high false-positive rate (as most small-for-gestational-age fetuses are not growth restricted). Here, we review 2 strategies that may improve the diagnostic accuracy of sonographic fetal biometry for fetal growth restriction. The first strategy involves serial ultrasound evaluations of fetal biometry. The information obtained through these serial assessments can be interpreted using several different approaches including fetal growth velocity, conditional percentiles, projection-based methods, and individualized growth assessment that can be viewed as mathematical techniques to quantify any decrease in estimated fetal weight percentile, a phenomenon that many care providers assess and monitor routinely in a qualitative manner. This strategy appears promising in high-risk pregnancies where it seems to improve the detection of growth-restricted fetuses at increased risk of adverse perinatal outcomes and, at the same time, decrease the risk of falsely diagnosing healthy constitutionally small-for-gestational-age fetuses as growth restricted. Further studies are needed to determine the utility of this strategy in low-risk pregnancies as well as to optimize its performance by determining the optimal timing and interval between exams. The second strategy refers to the use of fetal body proportions to classify fetuses as either symmetric or asymmetric using 1 of several ratios; these include the head circumference to abdominal circumference ratio, transverse cerebellar diameter to abdominal circumference ratio, and femur length to abdominal circumference ratio. Although these ratios are associated with small for gestational age at birth and with adverse perinatal outcomes, their predictive accuracy is too low for clinical practice. Furthermore, these associations become questionable when other, potentially more specific measures such as umbilical artery Doppler are being used. Furthermore, these ratios are of limited use in determining the etiology underlying fetal smallness. It is possible that the use of the 2 gestational-age-independent ratios (transverse cerebellar diameter to abdominal circumference and femur length to abdominal circumference) may have a role in the detection of mild-moderate fetal growth restriction in pregnancies without adequate dating. In addition, despite their limited predictive accuracy, these ratios may become abnormal early in the course of fetal growth restriction and may therefore identify pregnancies that may benefit from closer monitoring of fetal growth.

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

BackgroundCurrently, 2-dimensional ultrasound estimation of fetal size rather than fetal growth is used to define fetal growth restriction, but single estimates in late pregnancy lack sensitivity and may identify small for gestational age rather than growth restriction. Single or longitudinal measures of 3-dimensional fractional thigh volume may address this problem.ObjectiveWe sought to derive normal values for 3-dimensional fractional thigh volume in the third trimester, determine if fractional thigh volume is superior to 2-dimensional ultrasound biometry alone for detecting fetal growth restriction, and determine whether individualized growth assessment parameters have the potential to identify fetal growth restriction remote from term delivery.Study DesignThis was a longitudinal prospective cohort study of 115 unselected pregnancies in a tertiary referral unit (St Mary’s Hospital, Manchester, United Kingdom). Standard 2-dimensional ultrasound biometry measurements were obtained, along with fractional thigh volume measurements (based on 50% of the femoral diaphysis length). Measurements were used to calculate estimated fetal weight (Hadlock). Individualized growth assessment parameters and percentage deviations in longitudinally measured biometrics were determined using a Web-based system (iGAP; http://iGAP.research.bcm.edu). Small for gestational age was defined <10th and fetal growth restriction <3rd customized birthweight centile. Logistic regression was used to compare estimated fetal weight (Hadlock), estimated fetal weight (biparietal diameter–abdominal circumference–fractional thigh volume), fractional thigh volume, and abdominal circumference for the prediction of small for gestational age or fetal growth restriction at birth. Screening performance was assessed using area under the receiver operating characteristic curve.ResultsThere was a better correlation between fractional thigh volume and estimated fetal weight ((biparietal diameter–abdominal circumference–fractional thigh volume) obtained at 34-36 weeks with birthweight than between 2-dimensional biometry measures such as abdominal circumference and estimated fetal weight (Hadlock). There was also a modest improvement in the detection of both small for gestational age and fetal growth restriction using fractional thigh volume–derived measures compared to standard 2-dimensional measurements (area under receiver operating characteristic curve, 0.86; 95% confidence interval, 0.79–0.94, and area under receiver operating characteristic curve, 0.92; 95% confidence interval, 0.85–0.99, respectively).ConclusionFractional thigh volume measurements offer some improvement over 2-dimensional biometry for the detection of late-onset fetal growth restriction at 34-36 weeks.

Classifying neonatal growth outcomes: use of birth weight, placental evaluation and individualized growth assessment

Objective: To compare neonatal growth outcomes determined by birth weight (BW), placental assessment (Plac Assess) and individualized growth assessment (IGA). Methods: This retrospective analysis was carried out in 45 selected pregnancies at risk for fetal growth restriction. Serial fetal biometry was carried out in the 2nd and 3rd trimester. First and second trimester placental biomarkers, 2nd trimester uterine artery (Ut A) velocimetry and postnatal placental pathology were evaluated as indicators of placental insufficiency. At delivery, weight (WT), head circumference (HC) and crown–heel length (CHL) were measured. BWs were categorized as large-for-gestational-age (LGA), appropriate-for-gestational-age (AGA) and small-for-gestational age (SGA) (<10th, 10th–90th and >90th percentiles). In these categories, neonatal growth outcomes were classified as growth restricted (GR), normal (NORMAL) or macrosomic (MACRO) based on BW plus Plac Assess (Ut A velocimetry, biomarkers, pathology) or IGA [growth potential realization index profile (WT, HC and CHL)]. Results: There were 6 LGA, 14 AGA and 25 SGA neonates in this sample. All 14 AGA neonates were considered NORMAL by both IGA and BW + Plac Assess. All six LGA neonates were classified as MACRO by BW + Plac Assess but only four by IGA (the remaining two were NORMAL and high NORMAL). The 25 SGA cases could be divided into five subgroups based on IGA and BW + Plac Assess. The largest subgroup (56%) was GR and the next largest (24%) was NORMAL by both classification methods. In the remaining 20%, there was some evidence of GR but IGA and BW + Plac Assess were not in complete agreement. Conclusions: Agreement was good for all three methods in the LGA and AGA groups. The SGA group was heterogeneous but agreement between IGA and BW + Plac Assess was 89%. These results, using more sophisticated growth assessment methods, confirm placental insufficiency as a primary cause of growth restriction. Most normal and GR SGA neonates can be identified with conventional anatomical measurements if IGA is used.

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

Objective: To compare third-trimester size trajectory prediction errors (average transformed percent deviations) for three individualized fetal growth assessment methods.Methods: This study utilized longitudinal measurements of nine 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 and CPM) were used to calculate predicted values at ∼400 third-trimester time points. Percent deviations (%Dev) calculated at these time points using all three methods were expressed as percentages of IGA MA-specific reference ranges [transformed percent deviations (T%Dev)]. Third-trimester T%Dev values were averaged (aT%Dev) for each parameter. Mean ± standard deviation’s for sets of aT%Dev values derived from each method (IGA, PLM and CPM) were calculated and compared.Results: Mean aT%Dev values for nine parameters were: (i) IGA: −4.3 to 5.2% (9/9 not different from zero); (ii) PLM: −32.7 to 25.6% (4/9 not different from zero) and (iii) 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 (i) 5/9 being statistically significant (IGA versus PLM), (ii) 2/9 being statistically significant (IGA versus CPM) and (iii) 5/9 being statistically significant (PLM versus 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 the PLM approach for most but not all parameters. These results suggest that third-trimester size trajectories are best characterized by IGA in fetuses with normal growth outcomes.

The effect of maternal body mass index on fetal growth: use of individualized growth assessment and two-level linear modeling.

To determine the effect of maternal body mass index on fetal growth using individualized growth assessment and two-level linear modeling. A retrospective review of biometry in the second and third trimesters from 246 normal, term singleton fetuses was performed. Four to eight biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur diaphysis length (FDL) measurements per fetus were available and used to determine second-trimester growth rates. Expected third-trimester size trajectories were generated from these data and Percent Deviations [%Dev = ((observed - expected)/expected) × 100] were calculated. Two-level linear modeling was used to determine %Dev slopes and the effect of body mass index (BMI) on these slopes. Relationships between individual second- and third-trimester slopes and BMI were evaluated using linear regression. Linear regression analysis of second-trimester growth indicated no significant relationships between the fetal growth rate and the BMI in the second trimester [R(2) (adj): 0.0% to 1.0% except AC in one subgroup (5.6%)]. Regression analysis did not indicate a significant relationship (adj R(2) : 0%-0.2%) between BMI and third-trimester %Dev slopes for any anatomic parameter. Two-level statistical modeling showed no effect of BMI on BPD, AC, or FDL growth and only a moderate effect on the HC growth in the third trimester. Our findings indicate that the maternal BMI does not have an effect on fetal growth in either the second or the third trimester as determined with individualized growth assessment.

Individualized fetal growth assessment: critical evaluation of key concepts in the specification of third trimester size trajectories

Objectives: To characterize second and third trimester fetal growth using Individualized Growth Assessment methods in a larger cohort of fetuses with normal neonatal growth outcomes.Methods: A prospective longitudinal study of 119 pregnancies was performed from 18 weeks, MA, to delivery. Measurements of several 1D and 3D fetal size parameters were obtained from 3D volume data sets at 3–4 week intervals. Regression analyses were used to determine Start Points (SP) and Rossavik model (P = c {t} k + st) coefficients c. k and s for each parameter in each fetus. Second trimester growth velocity reference ranges were determined and size model specification functions re-established, the latter used to generate individual size models. Actual measurements were compared to predicted third trimester size trajectories using Percent Deviations. New age-specific reference ranges for the Percent Deviations of each parameter were defined using 2-level statistical modeling.Results: Rossavik models fit the data for all parameters very well (R2: 99%), with SP’s and k values similar to those found in much smaller cohorts. The c* values were strongly related to the second trimester slope (R2: 97%), as was predicted s* to estimated c* (R2: 54--95%). Rossavik models predicted third trimester growth with systematic errors close to 0%; random errors (95% range) ranged between 5.7 and 10.9% and 20.0 and 24.3% for 1D and 3D parameters, respectively.Conclusions: IGA procedures for evaluating second and third trimester growth are now established based on a larger cohort (4–6 fold larger). New, more rigorously defined, age-specific standards for the evaluation of third trimester size deviations are now available for nine anatomical parameters and a weight estimation procedure that incorporates a soft tissue parameter (fractional thigh volume). These results provide a means for more reliably assessing fetal growth on an individualized basis, thus minimizing the effect of biological differences in growth.

457: Individualized growth assessment in pregnancies complicated by gastroschisis

complicated by gastroschisis Sina Haeri, Russell Deter, Padmashree Woodham, Wesley Lee Baylor College of Medicine & Texas Children’s Hospital, Obstetrics & Gynecology, Houston, TX, Mercer School of Medicine & Medical Center of Central Georgia, Obstetrics & Gynecology, Macon, GA OBJECTIVE: Traditional fetal growth assessment has relied on the ultrasound (US) estimated fetal weight (EFW) and comparison with reference ranges. Unfortunately, in pregnancies complicated by gastroschisis, this has led to an overestimation of fetal growth restriction (FGR) due to the defect related abdominal circumference changes. Consequently, our objective was to examine growth using the Individualized Growth Assessment (IGA) with each fetus as its own control. STUDY DESIGN: In this cohort study of pregnancies complicated by gastroschisis, longitudinal US data for biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) were obtained. Second trimester-specific Rossavik models [P c(tk st] for these four anatomical parameters were used to generate expected third-trimester size trajectories with age-specific normal reference ranges. Observed and predicted measurements were compared by percent deviations. Subjects with percent deviation less than the normal range (BPD 0-0%, HC -0.11-0%, AC -0.05-0%, FL -0.27-0%) were classified as not having reached their growth potential for a specific parameter (cases). RESULTS: BPD, HC, and FL parameters exhibited normal size trajectories. For AC, 14 (56%) fetuses reached their individualized growth potential, while 11 (44%) did not. Compared to controls, those with impaired AC growth were more likely to demonstrate non-reassuring fetal heart rate tracing (36% vs. 0%, p 0.03), have a lower BW (2055 / 659 vs. 2886 / 813 grams, p 0.01), and required a longer length of stay (40.3 / 21.1 vs. 25.0 / 15.2 days, p 0.05). Subjects were also categorized based on birthweight as small for gestational age (SGA) vs. normal. SGA status did not predict adverse neonatal outcomes. CONCLUSION: IGA provides an alternative to conventional ultrasound measures of growth by allowing the fetus with gastroschisis to serve as its own control. IGA may serve as a superior tool in identifying fetuses with a tenuous post-natal course and allow for targeted management strategies.

Fetal nutritional status: diagnosis and future perspectives

Fetal nutritional status: diagnosis and future perspectives

Individualized growth assessment of fetal thigh circumference using three‐dimensional ultrasonography

To develop individualized growth assessment (IGA) standards for upper (ThC(u)) and middle (ThC(m)) fetal thigh circumferences using three-dimensional ultrasonography. A prospective, longitudinal sonographic study of 30 fetuses was performed beginning at 18 weeks' menstrual age. Second-trimester sonographic parameters were measured from three-dimensional volume data to establish IGA standards. Normal infant growth outcomes were confirmed using modified Neonatal Growth Assessment Scores (m(3)NGAS(51)). ThC(u) and ThC(m) were studied in more detail. Rossavik growth model specification procedures, based on the slopes of the second-trimester growth curves, were developed for both ThC(u) and ThC(m). Third-trimester growth trajectories and birth measurements were subsequently predicted for these parameters. Percentage deviations during the third trimester and percentage differences at actual birth age were used to compare observed and predicted measurements. The 95% ranges for Growth Potential Realization Index (GPRI) values for both types of thigh circumference were determined. Values for m(3)NGAS(51) using GPRI(ThC(u)), GPRI(ThC(m)) and GPRI(ThC(o)) (original method) were compared. The 30 newborns had no postnatal evidence of abnormal growth. Two examiners demonstrated a satisfactory measurement bias of mean +/- SD 2.1 +/- 3.6 (95% limits of agreement,-4.9 to 9.1)% for ThC(m) and 3.3 +/- 4.1 (95% limits of agreement,-4.8 to 11.4)% for ThC(u). Rossavik functions fitted parameter trajectories well, with mean R(2) values of 99.5 +/- 0.4% for ThC(u) and 99.6 +/- 0.3% for ThC(m). By fixing coefficients k at their mean values, their respective fits did not change, and the variabilities of coefficients c and s were significantly reduced. For ThC(u), coefficient c was significantly related to the second-trimester slope (R(2)=98.6%), as was s to c(R(2)=91.0%). For ThC(m), coefficient c was significantly related to the second-trimester slope (R(2)=98.6%), as was s to c(R(2)=85.6%). Third-trimester growth trajectories, derived from second-trimester slopes for individual fetuses, had third-trimester deviations of 0.07 +/- 3.7% for ThC(u) and-0.04 +/- 3.7% for ThC(m). Percentage differences at birth age were 16.8 +/- 10.2% for ThC(u) and 8.9 +/- 9.5% for ThC(m). With correction for systematic overestimations, the mean GPRI values were 103.7 (95% range, 90-121)% for ThC(u) and 101.6 (95% range, 88-118)% for ThC(m). Corresponding mean +/- SD m(3)NGAS(51) values, using GPRI(ThC(u)), GPRI(ThC(m)) and GPRI(ThC(o)), were 203 +/- 11%, 201 +/- 10% and 200 +/- 9%, respectively. Fetal thigh circumference can be measured reliably and evaluated using standard IGA methods. Both ThC(u) and ThC(m) give similar results in the third trimester but neonatal thigh circumference predictions are improved by using ThC(m). Corresponding GPRI(ThC(m)) values are closer to the ideal value of 100% and can be used in m(3)NGAS(51) calculations for assessment of neonatal growth outcome.

P34.04: Second trimester prediction of birth weight using individualized growth assessment

P34.04: Second trimester prediction of birth weight using individualized growth assessment