Hadlock Formulae Research Articles

Development and external validation of Indian population-specific Garbhini-GA2 model for estimating gestational age in second and third trimesters

A large proportion of pregnant women in lower and middle-income countries (LMIC) seek their first antenatal care after 14 weeks of gestation. While the last menstrual period (LMP) is still the most prevalent method of determining gestational age (GA), ultrasound-based foetal biometry is considered more accurate in the second and third trimesters. In LMIC settings, the Hadlock formula, originally developed using data from a small Caucasian population, is widely used for estimating GA and foetal weight worldwide as the pre-programmed formula in ultrasound machines. This approach can lead to inaccuracies when estimating GA in a diverse population. Therefore, this study aimed to develop a population-specific model for estimating GA in the late trimesters that was as accurate as the GA estimation in the first trimester, using data from GARBH-Ini, a pregnancy cohort in a North Indian district hospital, and subsequently validate the model in an independent cohort in South India. Data obtained by longitudinal ultrasonography across all trimesters of pregnancy was used to develop and validate GA models for the second and third trimesters. The gold standard for GA estimation in the first trimester was determined using ultrasonography. The Garbhini-GA2, a polynomial regression model, was developed using the genetic algorithm-based method, showcasing the best performance among the models considered. This model incorporated three of the five routinely measured ultrasonographic parameters during the second and third trimesters. To assess its performance, the Garbhini-GA2 model was compared against the Hadlock and INTERGROWTH-21st models using both the TEST set (N=1493) from the GARBH-Ini cohort and an independent VALIDATION dataset (N=948) from the Christian Medical College (CMC), Vellore cohort. Evaluation metrics, including root-mean-squared error, bias, and preterm birth (PTB) rates, were utilised to comprehensively assess the model's accuracy and reliability. With first trimester GA dating as the baseline, Garbhini-GA2 reduced the GA estimation median error by more than three times compared to the Hadlock formula. Further, the PTB rate estimated using Garbhini-GA2 was more accurate when compared to the INTERGROWTH-21st and Hadlock formulae, which overestimated the rate by 22.47% and 58.91%, respectively. The Garbhini-GA2 is the first late-trimester GA estimation model to be developed and validated using Indian population data. Its higher accuracy in GA estimation, comparable to GA estimation in the first trimester and PTB classification, underscores the significance of deploying population-specific GA formulae to enhance antenatal care. The GARBH-Ini cohort study was funded by the Department of Biotechnology, Government of India (BT/PR9983/MED/97/194/2013). The ultrasound repository was partly supported by the Grand Challenges India-All Children Thriving Program, Biotechnology Industry Research Assistance Council, Department of Biotechnology, Government of India (BIRAC/GCI/0115/03/14-ACT). The research reported in this publication was made possible by a grant (BT/kiData0394/06/18) from the Grand Challenges India at Biotechnology Industry Research Assistance Council (BIRAC), an operating division jointly supported by DBT-BMGF-BIRAC. The external validation study at CMC Vellore was partly supported by a grant (BT/kiData0394/06/18) from the Grand Challenges India at Biotechnology Industry Research Assistance Council (BIRAC), an operating division jointly supported by DBT-BMGF-BIRAC and by Exploratory Research Grant (SB/20-21/0602/BT/RBCX/008481) from Robert Bosch Centre for Data Science and Artificial Intelligence (RBCDSAI), IIT Madras. An alum endowment from Prakash Arunachalam (BIO/18-19/304/ALUM/KARH) partly funded this study at the Centre for Integrative Biology and Systems Medicine, IIT Madras.

Determination of fetal weight by ultrasonographic evaluation of fetal mid-thigh soft-tissue thickness in late third trimester

Background: Estimation of fetal weight is of utmost importance in the planning and management of uneventful labor. This study was done to compare the estimated fetal weight determined by Hadlock’s method and Scioscia’s formula (using femur length and mid-thigh soft-tissue thickness [MTSTT]) to the actual birth weight (ABW). Aims and Objectives: The objectives of this study were as follows: (1) To estimate fetal weight by Hadlock’s method and ultrasonographic evaluation of fetal MTSTT in late third trimester. (2) To correlate fetal weight derived by Hadlock’s method and ultrasonographic evaluation of fetal MTSTT with ABW. Materials and Methods: The study was conducted during the period November 2022–January 2023, at Sri Devaraj Urs Medical College, Tamaka, Kolar. Seventy-six pregnant ladies at term (between 37 and 40 weeks) were included in the study. Results: This study assessed validity of Hadlock formulae and Scioscia’s formulae for detecting fetal weight. For detection of fetal weight by Hadlock’s method, area under curve (AUC) was 0.961 and according to Scioscia’s formulae, AUC was 0.965. This study showed good agreement between fetal weight derived by Hadlock formulae and actual fetal weight (Kappa value – 0.725). There was also good agreement between fetal weight derived by Scioscia’s formulae and actual fetal weight (Kappa value – 0.745). Conclusion: The fetal weight derived by Scioscia’s formula was comparable to the actual fetal weight allowing us to rely on Scioscia’s formulae to detect fetal weight. Calculating fetal weight by measurement of fetal MTSTT serves as an additional tool for estimation of fetal weight along with the existing parameters, thereby increasing the likelihood for accurate fetal weight estimation.

ESTIMATION OF FETAL WEIGHT BY CLINICAL METHODS AND ULTRASOUND AND CORRELATING ITS ACCURACY WITH ACTUAL BIRTH WEIGHT IN TERM PREGNANCIES AT ANMMCH, GAYA, BIHAR

Objective:This study was to estimate the fetal weight in term pregnancy by clinical methods and ultrasound and to compare the results with actual birth weight (ABW). Material and Methods:This study was conducted at Department of Obstetrics and Gynaecology, Anugrah Narayan Magadh Medical College and Hospital, Gaya, Bihar from December 2019 to May 2020. It was a prospective study covering 200 pregnant women at term gestation. Results: Estimated birth weight by abdominal girth × symphysis fundal height (AG × SFH) formula was closest to the ABW (P = 0.060), as compared to the estimated birth weight by Johnson's formula (P = 0.000) and Hadlock's formula (P = 0.000). Therefore, of the three formulae studied, AG × SFH formula had better predictive value as compared to Johnson's and Hadlock's formulae. The accuracy of AG × SFH (Insler's formula) for estimating the fetal weight at term was found to be comparable to Hadlock's formula (P= 0.104). Conclusion: Clinical estimation of birth weight denitely has a role in the management of labor and delivery. AG × SFH is a simple, easy, costeffective, and universally applicable method to predict fetal birth weight which can be used even by paramedics like midwives and also in centers where ultrasound is not available.

Correlation between estimated fetal weight and weight at birth in infants with gastroschisis and omphalocele

Background An accurate estimated fetal weight (EFW) calculated with traditional formulae in cases of abdominal wall defects (AWDs) can be challenging. As a result of reduced abdominal circumference, fetal weight may be underestimated, which could affect prenatal management. Siemer et al. proposed a formula without the use of abdominal circumference, but it is not used in our protocols yet. Objectives Our aim was to evaluate the correlation of EFW and birth weight in fetuses with AWD by using Hadlock 1, Hadlock 2, and Siemer et al.’s formulae. Our secondary goal was to evaluate how often fetuses classified as small for gestational age (SGA) were in fact SGA at birth. Study design This was a retrospective cohort study of gestations complicated by gastroschisis and omphalocele at two tertiary-care centers in Brazil and Italy during an 8-year period. Of a total of 114 cases, 85 (44 cases of gastroschisis and 41 cases of omphalocele) met our criteria. Results The last prenatal scan was performed 5.2 (±4.1) days before birth. The mean gestational age at birth was 37.2 (±1.8) weeks. Correlation of EFW with birth weight was calculated with the three formulae with and without adjustment for weight gain between scan and birth, with the use of the Spearman coefficient. The correlation between EFW and weight at birth was positive according to all three formulae for the infants with gastroschisis. This finding was not confirmed in the infants with omphalocele. All formulae overestimated the number of SGA cases: although only 17.6% of fetuses were actually SGA at birth, the Hadlock formulae had classified nearly 35% of them as SGA, and Siemer et al.’s formula, 15.3%. Conclusion All three formulae yielded a good correlation between EFW in the last scan and birth weight in the infants with gastroschisis but not for those with omphalocele. Cases of SGA were overestimated.

Evaluation of Fetal Mid-Thigh Soft Tissue Thickness and Femur Length for Estimation of Fetal Birth Weight

Accurate calculation of fetal weight relies on two equally important factors: the use of a formula with strong intrinsic properties, and the use of sonographic biometric parameters that are not susceptible to errors in measurement. From a statistical perspective, the inclusion of multiple variables in a model improves multicollinearity chances and decreases each measurement's internal error. Precisely predicting estimated fetal weight during childbirth may have a significant impact on successful obstetric management, especially in the case of suspected macrosomia or low birth weight. Macrosomic fetuses can cause maternal and neonatal complications during childbirth, and low-born fetuses are at increased risk for perinatal morbidity and mortality. The main aim of the study was to assess the accuracy of measurement of mid-thigh soft tissue thickness and femur length, in estimation of expected fetal birth weight The study was conducted during the period January 2017 to August 2019, at Tanta University hospitals, Obstetrics & Gynecology department. 65 pregnant ladies at term (between 37-40weeks) were included in the study. Results: Mean difference between fetal weight by Hadlock formulae and actual fetal weight is -10.88g; percent difference is (0.32%). The difference statistically insignificant p>0.05. Mean difference between fetal weight by Scioscia’s formulae and Actual fetal weight is 2.83; the percent difference is (0.08%). The difference statistically insignificant p>0.05. Good agreement between Hadlock formulae and Actual Fetal Weight Kappa value (0.73).Also shows moderate agreement between Scioscia’s formulae and Actual Fetal Weight Kappa value (0.52). area under curve Hadlock formulae (0.79), Scioscia’s formulae (0.78) for detecting fetal weight ≥3500gm among pregnant women at 39-40 weeks of gestation. Conclusion: The mid-thigh soft tissue thickness and femur length can be used in estimation of expected fetal birth weight like as other sonographic parameters. The validity of Scioscia's formulae is not better than Hadlock formulae in detection of fetal weight less than 3500 gm. The validity of both formulae Scioscia's and Hadlock in detection of fetal weight more than 3500 gm. Reduced and cannot be dependable in extremes of weight.

Accuracy of sonographic estimation of weight in fetuses with abdominal wall defects.

Accurate estimation of fetal weight is essential in guiding management of fetuses with abdominal wall defects (AWDs), as growth restriction is an important predictor of perinatal morbidity and mortality. Several sonographic formulae are available involving multiple biometric parameters, but abdominal circumference measurements may underestimate weight in fetuses with AWDs. No formula has yet shown superior accuracy. The objectives of this study were to evaluate, in fetuses with gastroschisis and omphalocoele, the accuracy of a sonographic estimated fetal weight (EFW) formula proposed by Siemer and colleagues, specifically for use in fetuses with AWDs compared to the commonly used Hadlock IV formula in estimating fetal weight, and detecting small for gestational age (SGA) fetuses. A retrospective cohort of 113 fetuses with AWDs was identified from an Australian teaching hospital over 13years. Pregnancy data and sonographic fetal biometry parameters were obtained. The accuracy of each formula in predicting birthweight was compared using Bland-Altman limits of agreement, and the intraclass correlation coefficient between EFW and actual birthweight. Performance of each formula in detecting SGA fetuses was determined. The Siemer and Hadlock formulae have similar accuracies for predicting birthweight in fetuses with AWDs. The Hadlock formula has a higher detection rate for SGA<10th centile and<3rd centile compared to the Seimer formula (84% vs 68% and 83% vs 67% respectively), albeit with a higher false-positive rate. There is no clear clinical advantage in using the Siemer formula, which is specifically designed for fetuses with AWDs, over the Hadlock formula to estimate weight in fetuses with AWDs.

Validation of Hadlock's and Shepard Formulae of Fetal Weight Estimation in Eastern Region of Nepal

Introduction: Ultrasonography plays a pivotal role in present day obstetrics. It has been well recognized that the fetuses of extremes of the normal birth weight range are associated with increased perinatal morbidity, mortality and adverse development outcomes. Categorization of fetal weight into either the small or large for gestational age may lead to timed obstetric interventions that collectively represent significant departure from routine antenatal care.&#x0D; Objective: To compare the accuracy of Hadlock's 1, 2, 3, 4 and Shepard model in estimating expected fetal weight and its comparison with actual birth weight in our population at eastern region of Nepal.&#x0D; Methodology A prospective observational study was performed in the Department of Radiodiagnosis, Nobel Medical college and teaching hospital, Biratnagar, over a period of 6 months dated Jan 2018 to June 2018 using systematic random sampling with sample size estimated as 160, with 5% level of significance, 80% power of test and a maximum of 200 grams differences by our predicting model from actual mean weight. Singleton, term pregnancy (37- 42 weeks gestational age) verified with antenatal USG performed prior to 20 weeks' gestation. Pregnancies complicated by congenital anomalies and deliveries after 2 days of USG examination were excluded.&#x0D; Results: 159 pregnant ladies were enrolled in our study with mean age of 27.60 ± 5.633 years (range 18-43 years). The average (actual) birth weight recorded was 3450.79±438.73gms. The different formulae for estimating birth weight gave us similar results. Estimation of fetal weight by Shepard gave us a mean of 3340.80 ± 463.72. Hadlock1, Hadlock2, Hadlock3 and Hadlock4were 3546.55±429.92grams, 3491.18±439.49 grams, 3445.23 ±422.79grams, and 3446.12±418.43grams respectively.&#x0D; Conclusion: All four Hadlock formulae gave comparable results for fetal weight estimation including the Shepard formula; however, Shepard formula tends to underestimate fetal weight as compared to rest of the formulae. Among the Hadlock's, Hadlock 2 seems to show betier accuracy in fetal weight prediction in our population of study. The mean birth weight recorded using Hadlock 1 formula gave the beer correlation with the actual birth weight though the difference between four Hadlock formulae was all insignificant.

Analysis of the Performance of 11 Formulae for Fetal Weight Estimation in Preterm Fetuses with Abnormal Doppler Velocimetry - A Retrospective Multicenter Study.

To assess 11 formulae commonly used to estimate fetal weight in a population of premature fetuses who had abnormal Doppler velocimetry due to early-onset placental insufficiency. The performance of each formula was evaluated in subgroups of fetuses with expected growth and intrauterine growth restriction. Data were collected from fetuses and mothers who delivered at three Brazilian hospitals between November 2002 and December 2013. We used the following formulae: Campbell; Hadlock I, II, III, IV and V; Shepard; Warsof; Weiner I and II; and Woo III. We analyzed 194 fetuses. Of these, 116 (59.8%) were considered appropriate for gestational age (AGA), and 103 (53.1%) were male. The amniotic fluid volume was reduced in 87 (44.8%) fetuses, and the umbilical artery Doppler revealed absence or inversion of diastolic flow in 122 (62.9%) cases, and the analysis of the ductus venosus revealed abnormal flow in 60 (34.8%) fetuses. The Hadlock formulae using three or four fetal biometric parameters had low absolute percentage error in the estimated fetal weight among preterm fetuses with abnormal Doppler studies who were born within 5 days of the ultrasound evaluation. The results were not influenced by the clinical and ultrasound parameters often found in early-onset placental insufficiency. In this study, the formulae with the best performance for fetal weight estimation in the analyzed population were Hadlock I and IV, which use four and three fetal biometric parameters respectively to estimate the weight of preterm fetuses with abnormal Doppler studies.

Comparison of Estimation of Fetal Weight by Clinical Method, Ultrasonography and its Correlation with Actual Birth Weight in Term Pregnancy

Objective: To make a comparative evaluation of estimated fetal weight with actual birth weight by using: 1. Aymphysiofundal height x abdominal girth (dares formulae) 2. Ultrasonography (hadlock formulae). Materials and Methods: A prospective comparative study was carried out at the Obstetrics and Gynecology Department and USG section of Department of Radiodiagnosis of Dr. Vasantrao Pawar Medical College and research centre from August 2014 to December 2016, to compare the accuracy of clinical and ultrasonographic estimation of foetal weight with actual birth weight at term. One hundred pregnant women who fulfilled the inclusion criteria had their foetal weight estimated independently using clinical and ultrasonographic methods. Results: About three fourth of the study subjects were in normal weight range of 2.5-4 Kg while 16% were LBW and 8% were VLBW babies. Both Dare's and Hadlock's formulae shows good co-relation with actual birth weight across all weight ranges (r- 0.77 and 0.72; p&lt;0.05 for both) with best correlation observed at weight range of 2.5 to 3.5 Kg. Correlation was slightly lower at extremes of weight at both end. In present study, on comparing prospectively clinical and sonographic methods of predicting birth weight prior to induction of labor at term, we found that clinical estimates appear to be as accurate as ultrasonographic ones. Conclusion: In developing country where ultrasound is not available in many health care delivery system, clinical estimation of foetal weight is an easy, cost effective and simple method.

Comparison of Estimation of Fetal Weight by Clinical Method, Ultrasonography and its Correlation with Actual Birth Weight in Term Pregnancy

Objective: To make a comparative evaluation of estimated fetal weight with actual birth weight by using: 1. Aymphysiofundal height x abdominal girth (dares formulae) 2. Ultrasonography (hadlock formulae). Materials and Methods: A prospective comparative study was carried out at the Obstetrics and Gynecology Department and USG section of Department of Radiodiagnosis of Dr. Vasantrao Pawar Medical College and research centre from August 2014 to December 2016, to compare the accuracy of clinical and ultrasonographic estimation of foetal weight with actual birth weight at term. One hundred pregnant women who fulfilled the inclusion criteria had their foetal weight estimated independently using clinical and ultrasonographic methods. Results: About three fourth of the study subjects were in normal weight range of 2.5-4 Kg while 16% were LBW and 8% were VLBW babies. Both Dare’s and Hadlock’s formulae shows good co-relation with actual birth weight across all weight ranges (r- 0.77 and 0.72; p<0.05 for both) with best correlation observed at weight range of 2.5 to 3.5 Kg. Correlation was slightly lower at extremes of weight at both end. In present study, on comparing prospectively clinical and sonographic methods of predicting birth weight prior to induction of labor at term, we found that clinical estimates appear to be as accurate as ultrasonographic ones. Conclusion: In developing country where ultrasound is not available in many health care delivery system, clinical estimation of foetal weight is an easy, cost effective and simple method.

Prospective assessment of INTERGROWTH-21st and World Health Organization estimated fetal weight reference curves.

To assess the suitability of the new INTERGROWTH-21st and World Health Organization (WHO) estimated fetal weight (EFW) references in a Southern Chinese population. A secondary aim was to determine the accuracy of EFW by assessing the difference between EFW and actual birth weight. This was a prospective cross-sectional cohort study. Viable singleton pregnancies at 11-13 weeks' gestation were recruited to undergo a single standardized fetal biometric scan after 20 weeks. The gestational age at which the scan was performed was allocated randomly at the time of recruitment. EFW was predicted using both the Hadlock and INTERGROWTH-21st weight estimation model formulae. Population-specific EFW references were constructed. Z-scores were used to compare these references against the INTERGROWTH-21st and WHO international size references. Gestational-age-adjusted projection was used to assess the difference between EFW on the day of delivery and birth weight for fetuses having biometry scans ≥ 34 weeks. Fetuses of 970 participants had biometry scans. The median number of scans per gestational week was 48 (interquartile range, 43-53). Z-score comparison indicated that the WHO 10th , 50th and 90th centiles of the EFW reference were consistently higher than the corresponding local centiles, whilst the INTERGROWTH-21st 10th centile was lower. Fewer than 2% of fetuses scanned at or after 34 weeks would be considered as potentially large-for-gestational age, irrespective of which model was used to predict weight. Adopting the WHO international reference would result in approximately one in six fetuses being regarded as potentially small-for-gestational age, 50% more than the number determined using a population-specific reference. Systematic errors of extrapolated EFW were similar, ranging from 5.5% to 7.4%. Centers seeking to use new references, such as the INTERGROWTH-21st and/or WHO international references, as a means of determining whether a fetus is small- or large-for-gestational age, would be advised to assess the suitability of these references within their own population using standardized methodology. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

The effect of severe maternal obesity on the accuracy of ultrasonographic fetal weight estimation: a prospective cohort study

ObjectivesTo assess the accuracy of fetal biometry measurements in predicting birthweight and to compare serial fetal biometry measurements in women with very severe obesity and lean controls.Methods174 very severely obese...

Accuracy of ultrasound estimation of fetal weight at term

ObjectiveAn increasing number of ultrasound departments, often under substantial workload pressures, have stopped scanning for ‘growth’ at term, claiming that ultrasound biometry is not accurate in late pregnancy. We wanted...

Which is the most accurate formula to estimate fetal weight in women with severe preterm preeclampsia?

Objective. To identify the most accurate formula to estimate fetal weight (EFW) from ultrasound parameters in severe preterm preeclampsia.Methods. In a prospective study, serial ultrasound assessments were performed in 123 women with severe preterm preeclampsia. The EFW, calculated for 111 live born, normal, singleton fetuses within 7 days of delivery using 38 published formulae, was compared to the actual birth weight (ABW). Accuracy was assessed by correlations, mean (absolute and signed) (%) errors, % correct predictions within 5–20% of ABW and limits of agreement.Results. Accuracy was highly variable. Most formulae systematically overestimated ABW. Five Hadlock formulae utilizing three or four variables and Woo 3 formula had the highest accuracy and did not differ significantly (mean absolute % errors 6.8–7.2%, SDs 5.3–5.8%, > 75% of estimations within 10% of ABW and 95% limits of agreement between -18/20% and +14/15%). They were not negatively affected by clinical variables but had some inconsistency in bias over the ABW range. All other formulae, including those targeted for small, preterm or growth restricted fetuses, were inferior and/or affected by multiple clinical variables.Conclusion. In this GA window, Hadlock formulae using three or four variables or Woo 3 formula can be recommended.

Prediction of birth weight using fetal thigh and upper-arm volumes by three-dimensional ultrasonography in a Brazilian population

Objective. To assess the accuracy of three-dimensional (3DUS) upper-arm (VolArm) and thigh (VolTh) volume measurements in the prediction of birth weight (BW).Methods. A cross-sectional study involving 81 live singletons was performed. VolArm and VolTh were obtained using 3DUS multiplanar mode with 5 mm slices. Linear and polynomial regressions were calculated to determine the best formula to predict BW using VolArm and VolTh. Analysis of variance was used to compare errors in BW using these formulae and using Shepard's and Hadlock's formulae. The interclass correlation coefficient (ICC) was used to assess intra and interobserver variability of measurements.Results. The best formula to predict BW based on VolArm was a simple linear equation (BW = 803.91 + 39.89VolArm), and for VolTh it was a second degree polynomial equation (BW = 32.37VolTh − 0.06VolTh2). A third formula using both parameters was also constructed (BW = 792.87 + 22.81VolArm + 7.54VolTh). The error (E), percent error (PE), absolute error (AE) and absolute percent error (APE) for the BW prediction using VolArm were 0 g, 163.4 g, 0.5% and 5.4%, respectively. The same results for E, PE, AE and APE using VolTh were 0.99 g, 155.5 g, 0.3% and 5.2% and for the combined formula using both VolArm and VolTh the E, PE, AE and APE were 0 g, 138.4 g, −0.4% and 4.6%, respectively. VolArm and VolTh were highly reproducible with intraobserver ICC of 0.98 and 0.99 and interobserver ICC of 0.96 and 0.97, respectively.Conclusions. BW estimated through formulae that use the fetal arm and thigh volumes assessed through 3DUS are not superior to two-dimensional formulae.

Incorporation of femur length leads to underestimation of fetal weight in asymmetric preterm growth restriction

To review the performance of a variety of biometry formulae for estimated fetal weight (EFW) in the management of severely growth restricted fetuses with abnormal umbilical artery Doppler at a single perinatal institution. Forty-three pregnancies were retrospectively reviewed. Inclusion criteria were: chromosomally/ structurally normal fetus; complete ultrasound biometry at < or = 7 days from delivery; EFW < 10(th) centile; absent/reversed end-diastolic flow in the umbilical arteries; and delivery at < 32 + 6 weeks. EFW accuracy and precision were compared among nine formulae utilizing combinations of head circumference (HC), biparietal diameter (BPD), abdominal circumference (AC) and femur length (FL) measurements. Twenty-six (60.5%) fetuses showed asymmetric growth (HC/AC ratio > 95(th) centile). Analysis of the systematic and random errors associated with each formula showed that the birth weight of asymmetrically-grown fetuses was most closely approximated by the Hadlock equation that utilized BPD and AC measurements only. The birth weight of symmetrically-grown fetuses was most closely approximated by EFW derived from Hadlock equations that utilized > or = three biometry measurements, including FL. Incorporation of FL into Hadlock formulae led to significant underestimation of birth weight in the fetuses with asymmetric growth (mean percentage error +/- SD: EFW(FL-AC), -13.3 +/- 9.8%; EFW(BPD-FL-AC), -10.8 +/- 9.8%; EFW(HC-FL-AC), -11.8 +/- 9.3%; EFW(BPD-HC-FL-AC), -11.7 +/- 9.5%; P < 0.001). The same equations were accurate in fetuses with symmetric growth (EFW(FL-AC), 3.1 +/- 10.0%; EFW(BPD-FL-AC), 1.0 +/- 8.9%; EFW(HC-FL-AC), 0.3 +/- 8.7%; EFW(BPD-HC-FL-AC), 0.4 +/- 15.5%). Use of the best performing equation (Hadlock 3), which does not include FL, to estimate weight in asymmetrically-grown fetuses over 28 weeks' gestation, would have reduced the proportion of those with an underestimation of fetal weight of > 100 g from nine (50.0%) to three (16.7%). Biometry methods that exclude FL should be considered in asymmetric intrauterine growth restriction associated with abnormal umbilical artery Doppler waveforms.

Estimativa de peso ao nascimento utilizando a ultrassonografia bidimensional e tridimensional

Assess and compare accuracy of birth weight prediction using a combination of two-dimensional (abdominal circumference - AC and femur length - FL) and three-dimensional parameters (fetal arm -VolArm and thigh -VolTh volumes). A cross sectional study was carried out involving 78 singleton, live, euploid fetuses without structural malformations born within 48 hours after ultrasonography. VolArm and VolTh were obtained by three-dimensional ultrasound using the multiplanar mode at 5 mm intervals. AC and FL were measured by two-dimensional ultrasound. Linear and polynomial regressions were calculated to determine the best formula to predict birth weight using VolArm, VolTh , CA and FL. ANOVA was used to compare errors in birth weight prediction using this formula and those obtained using the Shepard and Hadlock formulae. The best formula for prediction of birth weight was a simple linear regression (Weight = -1486.1 + 60.5AC + 140.57FL + 16.6VolArm + 4.8VolTh), R2= 0.932. The error (E), absolute error (AE), percent error (PE) and absolute percent error (APE) for this new formula were 0 g, 0.2%, 112.2 g and 3.7%. This new formula had smaller E, AE, PE and APE than the Shepard formula and smaller AE and APE than Hadlock s formula. A formula using VolArm, VolTh, AC and FL was more accurate for prediction of birth weight than formulae using only two-dimensional parameters.

Prediction of birth weight using fetal thigh and upper-arm volumes by three-dimensional ultrasonography in a Brazilian population

To assess the accuracy of three-dimensional (3DUS) upper-arm (VolArm) and thigh (VolTh) volume measurements in the prediction of birth weight (BW). A cross-sectional study involving 81 live singletons was performed. VolArm and VolTh were obtained using 3DUS multiplanar mode with 5 mm slices. Linear and polynomial regressions were calculated to determine the best formula to predict BW using VolArm and VolTh. Analysis of variance was used to compare errors in BW using these formulae and using Shepard's and Hadlock's formulae. The interclass correlation coefficient (ICC) was used to assess intra and interobserver variability of measurements. The best formula to predict BW based on VolArm was a simple linear equation (BW = 803.91 + 39.89VolArm), and for VolTh it was a second degree polynomial equation (BW = 32.37VolTh - 0.06VolTh(2)). A third formula using both parameters was also constructed (BW = 792.87 + 22.81VolArm + 7.54VolTh). The error (E), percent error (PE), absolute error (AE) and absolute percent error (APE) for the BW prediction using VolArm were 0 g, 163.4 g, 0.5% and 5.4%, respectively. The same results for E, PE, AE and APE using VolTh were 0.99 g, 155.5 g, 0.3% and 5.2% and for the combined formula using both VolArm and VolTh the E, PE, AE and APE were 0 g, 138.4 g, -0.4% and 4.6%, respectively. VolArm and VolTh were highly reproducible with intraobserver ICC of 0.98 and 0.99 and interobserver ICC of 0.96 and 0.97, respectively. BW estimated through formulae that use the fetal arm and thigh volumes assessed through 3DUS are not superior to two-dimensional formulae.