Sonographic Weight Estimation Research Articles

Effect of Maternal Body Mass Index on The Accuracy of Sonographic Estimation of Foetal Weight in Late Gestation

Effect of Maternal Body Mass Index on The Accuracy of Sonographic Estimation of Foetal Weight in Late Gestation

Vaginal delivery rate by near delivery sonographic weight estimation and maternal stature among nulliparous women.

We evaluated the risk for cesarean delivery among term nulliparous women, categorized by maternal stature and recent sonographic estimated fetal weight (EFW). A retrospective study including singleton deliveries of nulliparous women between 2011 and 2020, with sonographic EFW within 1week of delivery. We categorized maternal height into five groups: ≤150, 151-155, 156-160, 161-165, and ≥166 cm. Fetal weight estimation was categorized into five groups as well: ≤2500 g, 2501-2999, 3000-3499, 3500-3999, and ≥4000 g. Overall, 13 107 deliveries were included. The cesarean delivery rate was inversely correlated with maternal height, ranging from 41.0% in group 1 to 13.1% in group 5. The vaginal delivery rate ranged from 33.3% in maternal height group 1 with EFW of ≥4000 g to 85% in maternal height group 5 with EFW of ≤2500 g. In weight categories above 2500 g, maternal height correlated significantly with vaginal delivery rate, except in weight category ≥4000 g in which vaginal delivery rate ranged around 30% in maternal height categories 1-3 and increased significantly in groups 4-5 to 50-60%. In multivariable logistic regression analysis, EFW was independently associated with CD for EFW categories 3500-3999 and ≥4000 g [aOR 95% CI 1.49 (1.08-2.06) and 4.39 (2.97-6.50), respectively]. Maternal height was negatively associated with CD [aOR 95% CI 0.67 (0.64-0.70)] for each increase in maternal height group. Cesarean delivery rate was inversely correlated with maternal height, ranging from 41.0% among women ≤150 cm to 13.1% among women ≥166 cm. Maternal height and EFW of ≥3500 g are independently associated with CD rates among term nulliparous women.

Analysis of factors influencing ultrasound-based fetal weight estimation.

Determining the mean deviation between estimated fetal weight (EFW) measured by ultrasound biometry and the real final birth weight and defining the factors influencing the accuracy of weight estimation. Estimated weight of the fetus before birth is valuable information for obstetricians particularlyin choosing the method, management, and timing of delivery. The retrospective study analyzed 331 medical records of induced labor between January and June 2021. Fetal weight estimation was calculated using Hadlock formulas. The anamnestic data were obtained from medical records, namely: maternal age, maternal BMI, parity, date of the last ultrasonography (USG) before delivery, fetal presentation, placental location, EFW (including the physician's name performing the measurement, and time of the measurement), gestational age of the fetus, date of birth, fetal gender, neonatal weight and length. The correlations between the weight deviation and other factors were expressed using the Pearson and Phik (Φk) correlation coefficients. The Bland Altman method was used to visualize the correspondence between the two variables. The hypotheses were based on the acquired knowledge and then tested by Mann-Whitney U, Kruskal-Wallis, and ANOVA statistical tests, as required by the hypotheses and input data. The mean EFW in the studied group was 3,459 ± 435 g, and the mean actual birth weight was 3,508 ± 508 g. The mean absolute deviation between monitored weight parameters was 260.27 g. The mean real birth weight was higher compared to EFW by 4.873g. A significant effect on EFW was observed for the following factors: time interval between sonographic weight estimation and delivery (less than 7 days), high maternal BMI (> 30 kg/m2), maternal age, and neonatal weight and length. The factors of fetal presentation, placental location, amniotic fluid volume, fetal gender, gestational age, parity, or those of examiner did not seem to impact EFW accuracy in our study. The time interval between sonographic weight estimation and delivery (shorter than 7 days), maternal BMI over 30 kg/m2, maternal age, neonatal weight and length are all factors significantly associated with the accuracy of ultrasound-based fetal weight estimation (Tab. 2, Ref. 13). Text in PDF www.elis.sk Keywords: ultrasound, biometry, fetal weight estimation.

Evaluation of cardiac sphericity index among intrauterine growth restriction and normal fetuses

Foetal growth restriction (FGR) describes the pregnancy complications of pathological reduced foetal growth, leading to significant perinatal mortality and morbidity, and subsequent long-term cardiovascular outcomes. This prospective case-control study was performed on pregnant women referred to the hospitals of Tehran University of Medical Sciences in 2017–2019. All pregnant women underwent ultrasound scan and doppler sonography. FGR was defined as a sonographic estimation of foetal weight below the tenth percentile for a given gestational age. Cardiac sphericity index, including basal-apical length (BAL), transverse length (TL), global sphericity index (GSI), umbilical artery pulsatility index (PI), middle cerebral artery (MCA) PI and cerebroplacental ratio (CPR) were assessed. Mean gestational age in FGR and control groups were 233.90 ± 22.00 days and 229.00 ± 25.02 days, respectively. Foetal size index and estimated foetal weight in FGR foetuses were significantly lower than the control group (p < .05). BAL, TL and GSI were significantly affected by FGR (p = .0001, p = .018 and p = .0001, respectively). Abnormal GSI, MCA PI, umbilical artery PI and CPR were significantly more prevalent among FGR foetuses (p = .017, p = .0001, p = .0001 and p = .0001, respectively). Cardiac sphericity index, as well as uterine PI, MCA PI and CPR, were the determinants of FGR in foetuses with normal Doppler and abnormal GSI. IMPACT STATEMENT What is already known on this subject? Foetal growth restriction (FGR) describes the foetus that does not grow to its expected biological potential in utero, and is a relatively common complication of pregnancy. FGR is accosted with negative birth outcomes and long-term cardiovascular outcomes. One of the indicators of FGR is cardiac sphericity. What do the results of this study add? The findings of this study revealed that the cardiac sphericity index as well as umbilical PI, MCA PI and CPR ratio change in FGR foetuses. What are the implications of these findings for clinical practice and/or further research? It is recommended that more studies be performed to follow FGR foetuses longitudinally and evaluate the long-term cardiac abnormalities in infancy and childhood and compare it between FGR foetuses and normal foetuses.

907 2D Sonographic estimation of placental weight at 20 weeks correlates with delivery placental weight

Small placentae are associated with obstetric complications. Sonographic estimated placental volume (EPV) is correlated with adverse outcomes but is not recommended in societal guidelines because proposed techniques require specialized training or equipment. We hypothesize that the Volume of a Cylinder formula using simple 2D measurements is as accurate at predicting placental weight at delivery as a previously described method. This is a prospective observational study. 2D imaging techniques were used to measure placental width, depth, height, and maximal thickness at 12, 20, and 36 weeks, and EPV was calculated using two different formulae: Volume of a Cylinder and Volume of a Shell. All patients who delivered at term and for whom placental weight at delivery was obtained were included in this analysis. Correlation between EPV and placental weight at delivery was determined using the Spearman correlation coefficient. Regression analysis was performed to determine the association between EPV with delivery placental weight. Of 148 patients enrolled in this study and who met inclusion criteria, 64 patients had measurements taken at 12 weeks, 61 patients at 20 weeks, and 53 patients at 36 weeks (Table 1). Both formulae correlated with placental weight at delivery: Cylinder correlation coefficient at 20 weeks 0.42 (p < 0.001), 36 weeks 0.31 (p<0.5), Shell correlation coefficient at 20 weeks 0.46 (p <0.001), 36 weeks 0.40 (p<0.01). In linear regression analysis, both formulae at 20 weeks were associated with placental weight at delivery, with Cylinder and Shell parameter estimates of 0.29 (p<0.01) and 0.27 (p = 0.02) respectively. There was no correlation between either volume assessment at 12 weeks with final placental weight at delivery. These data show that EPV at 20 weeks using standard 2D measurements correlate with placental weight at delivery as well as a more complex approach. Future studies are needed to determine if estimating placental weight using this approach is predictive of adverse pregnancy outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Accuracy of Prediction of Birth Weight by Fetal Ultrasound

Introduction: Fetal weight estimation using ultrasonography (USG) is beneficial for the better feto-maternal outcome. This study was done to determine the accuracy of prediction of birth weight by fetal ultrasound.&#x0D; Methods: This was a cross-sectional study carried out in the Department of Radio diagnosis, Lumbini Medical College and Teaching Hospital (LMCTH), Palpa, Nepal from1st June to 31st December 2018.Fetal weight was calculated by USG in 325 women using Hadlock’s formula and correlated with birth weight.&#x0D; Results: Our study showed that fetal ultrasound using Hadlock’s formula has error in estimation of fetal weight by 189gm (SD: 111 gm). In 91.3% of the cases, there was an error of estimation by less than 10% compared to actual weight.&#x0D; Conclusion: It can be concluded that sonographic estimation of birth weight can be recommended to yield a better prediction of birth weight and to further evaluate fetal well-being.

The effect of fetal weight on the accuracy of sonographic weight estimation among women with diabetes

Objective The assessment of sonographic estimated fetal weight (EFW) enables identification of fetuses in the extremes of weight, thus aiding in the planning and management of peripartum care. There are conflicting reports regarding the accuracy of EFW in diabetic mothers. We aimed to study the factors associated with the accuracy of EFW at term, specifically the role of gestational and pre-gestational diabetes in this setting. Methods A retrospective study including all women carrying singleton term gestations who delivered within a week following a sonographic fetal weight estimation between 2011 and 2019. Accurate EFW was defined as within 10% of the actual birthweight. We allocated the study cohort into two groups: (1) Accurate EFW (2) inaccurate EFW. Both groups were compared in order to identify factors associated with the inaccuracy of EFW. Results Overall, 41,263 deliveries were available for evaluation, including 412 (1.0%) deliveries among women with pre-gestational diabetes and 4,735 (11.5%) among women with gestational diabetes. Of them, 7,280 (17.6%) had inaccurate EFW. Inaccurate EFW was associated with nulliparity, OR 0.82 [95% CI] (0.78–0.87), oligohydramnios, OR 0.81 [95% CI] (0.71–0.93), pregestational diabetes, OR [95% CI] 0.61 (0.50–0.79), and extremity of fetal weight; <2,500 grams–OR [95% CI] 0.37 (0.33–0.41) and >4,000 grams OR [95% CI] 0.52 (0.48–0.57). On multiple regression analysis, the following factors were independently associated with inaccurate EFW: pregestational diabetes, OR [95% CI] 0.58 (0.46–0.73), p < .001, nulliparity, OR [95% CI] 0.86 (0.82–0.91), p < .001 and higher fetal weight (for each 500 grams), OR [95% CI [1.25 (1.21–1.30), p < .001. On analysis of different weight categories, pregestational diabetes was associated with inaccurate EFW only in those with birthweight >3,500 grams, OR [95% CI] 0.37 (0.24–0.56) (p < .001). Conclusion Among pregestational diabetic women, the accuracy of sonographic EFW when assessed to be >3,500 grams is questionable. This should be taken into consideration when consulting women and planning delivery management. Synopsis Among pregestational diabetic women, the accuracy of estimated sonographic fetal weight higher than 3,500 grams is of limited accuracy.

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.

Differences in fetal growth patterns between twins and singletons*

Objective: Twin fetus growth is delayed during the third trimester compared to singletons. Whether this phenomenon should be considered a normal physiologic characteristic of twins or a pathologic process inherent to twin pregnancies is currently unclear. Information on the growth rate of the individual fetal biometric indices may provide more insight into the mechanisms underlying these differences between twins and singletons. Our aim was to compare fetal growth pattern between twin and singleton fetuses.Methods: This was a retrospective study of women with an uncomplicated twin pregnancy who underwent sonographic fetal weight estimation between 16 and 38 weeks’ gestation in a single referral center. Twins-specific regression models were generated for biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and fetal weight as a function of gestational age and were compared to published singletons-based curves.Results: Overall 543 women were eligible for the study and underwent a total of 3401 sonographic weight estimations. Estimated weight of twin fetus emerged as lower than that of singletons starting at 26 weeks of gestation, and these differences increased with gestational age, reaching a mean difference of 300–350 g or of ∼10% at term. The growth of all four biometric indices was slower in twins compared to singletons, but the differences were most pronounced for AC which had the largest relative contribution to the lower fetal weight in twins (51.7 ± 7.3%), while the relative contribution of FL, HC, and BPD was smaller (26.4 ± 10.7, 15.5 ± 3.0, and 6.4%±5.7%, respectively). This was also reflected by a higher HC/AC ratio in twins compared with singletons starting at 22 weeks of gestation. The likelihood of a twin fetus being diagnosed as small for gestational age (fetal weight <10th percentile) was significantly lower when the newly developed twins-based curves (rather than singletons-based curves) were used (OR: 0.39, 95%-CI: 0.34–0.44).Conclusion: Twin fetus experience slowing of growth beginning at ∼26 weeks of gestation and a greater degree of asymmetric growth pattern compared with singletons. These findings suggest that the slower growth of twins may reflect a state of “relative growth restriction” compared with singleton gestations.

Accuracy of Ultrasound in Estimating Fetal Weight at Term

AbstractBackground: To compare the accuracy of different sono-graphic formulae for fetal weight estimation at term.Material and Methods: Comparative cross-sectional study to evaluate 8 different formulae using 300 sonographic weight estimations performed within 24 hours before delivery. Using correlation coefficient, regression analysis and Bland and Altman method, to compare between the studied formulae with each other and knowing the effect the different fetal biometric indices on accuracy of estimates by ultrasound.Results: A considerable variation in the accuracy of the different formulae was found. For Birth Weights (BWs) in the range of 2500 to 3500g, formulae based on 3 or 4 fetal biometric indices were significantly more accurate than formulae that incorporated only 1 or 2 indices. The accuracy of formulae decreased at the extreme of birth weight >_4000gs, leading to underestimation of ABW (actual birth weight).Conclusion: We conclude that to improve the accuracy of fetal weight estimation, sonographic formulae that are based on 3 or 4 fetal biometric indices should be preferred.

Longitudinal Assessment of Examiner Experience and the Accuracy of Sonographic Fetal Weight Estimation at Term.

To evaluate the influence of examiner experience on the accuracy of sonographic weight estimation and to further analyze examiners' individual learning curves. In this multicenter study, 4613 sonographic weight estimations performed by 18 examiners at the beginning of their ultrasound training were included. To assess the effect of experience on the accuracy of weight estimation, a multivariable mixed regression model analysis was performed, with percentage error and absolute percentage error as outcome variables and the examiner, the examiner's experience (number of examinations), birth weight, gestational age, scan-to-delivery interval, and maternal body mass index as fixed effects and the perinatal center as random intercepts. To further analyze the individual learning curves of the examiners, the cumulative summation technique was used. Regression analyses showed a significant influence of the number of examinations on the accuracy of sonographic weight estimation after adjustment for the above-mentioned parameters (P < .001). A typical learning curve with improving accuracy was found until approximately 200 examinations. Between 200 and 300 examinations, the diagnostic performance started to deteriorate again, with a continuous decrease until the end of the study period. Cumulative summation charts representing individual learning curves varied greatly between different examiners. These findings indicate the great importance of continuous quality control systems in sonographic weight estimation.

Reliability of Sonographic Estimation of Fetal Weight: A Study of Three Tertiary Hospitals in Nigeria.

Context:There is a dearth of sonologists in Nigeria, yet sonographic estimation of actual birth weight (ABW) is important in antenatal care.Aim:To determine the reliability of estimated fetal weight (EFW) by sonographers and sonologists in Lagos Nigeria.Settings and Design:In the cross-sectional study, a convenience sample of 663 healthy women with singleton pregnancy at term was selected. Ethical approval for the study design and consent of participants were obtained.Subjects and Methods:Three sonographers and three sonologists used a single ultrasound scanner with Hadlock-3 algorithm to measure biparietal diameter, abdominal circumference, and femur length in three centers while three midwives used a single neonatal weighing scale to measure ABW.Statistical Analysis Used:Medical® statistical software version 12.5 was used to analyze data. Descriptive and inferential statistics, as well as Bland/Altman plots were used to determine reliability of EFWs. Results were tested for statistical significance at P ≤ 0.05.Results:Majority (76.2%) of babies had normal weight while mean EFW and ABW were 3.50 ± 0.10 kg and 3.45 ± 0.12 kg, respectively and the difference between them is not statistically significant (P > 0.05). For sonographers and sonologists in each center, mean error and coefficient of variation were very small while Pearson's correlation coefficient as well as intra- and interclass correlation coefficients was very high.Conclusion:Independent estimation of ABW by sonographers in Lagos metropolis was very reliable. Sonography was also highly reliable in predicting macrosomia.

Sonographic weight estimation in small for gestational age fetuses

Purpose: To determine the accuracy of sonographic weight estimation (WE) for small for gestational age (SGA) fetuses, and to further differentiate the evaluation between fetuses being symmetric and asymmetric SGA.

Accuracy of sonographic fetal weight estimation: influence of the scan-to-delivery interval in combination with the applied weight estimation formula.

To evaluate the influence of the time interval between examination and delivery on the accuracy of sonographic fetal weight estimation (WE). 8723 singleton pregnancies were included in this retrospective cohort study. Fetuses were divided into eight groups with regard to the time interval between estimation and delivery (group 1: 0days; group 2: 1-3days; group 3: 4-7days; group 4: 8-14days; group 5: 15-21days; group 6: 22-28days; group 7: 29-35days; group 8: 36-42days). The accuracy of WE was compared between the different time interval groups and five commonly used formulas using means of percentage errors (MPE), medians of absolute percentage errors, and proportions of estimates within 10% of actual birth weight. In group one, the Hadlock I and Warsof formula showed a systematic underestimation of fetal weight (negative MPEs). No systematic error was found with the Hadlock II formula and the equations of Merz and Shepard showed a systematic overestimation (positive MPEs). MPE values of the Hadlock I, II and Warsof formulas were closest to zero in WEs of group two. From group three to six, MPE values decreased continuously. With the Merz and Shepard equations MPEs were closest to zero in group four. The best accuracy of sonographic WE with most of the commonly used equations is achieved within a scan-to-delivery interval of 1week.

OC22.03: Sonographic weight estimation of small‐for‐gestational age fetuses: is the optimal model related to fetal body proportions?

OC22.03: Sonographic weight estimation of small‐for‐gestational age fetuses: is the optimal model related to fetal body proportions?

Advances in clinical estimation of foetal weight before delivery

Accurate estimation of foetal weight is of paramount importance before delivery. Clinical estimation of foetal weight is an important and necessary skill in management of obstetrics patients because of its simplicity; and if it is found to be as accurate as sonographic measurement as some studies suggest, it may be considered for screening of foetal weight especially in low-resource settings where ultrasound is unavailable. The aim of this review is to search for various literatures where clinical methods of foetal weight estimation were used and to examine these methods critically for possible recommendation for their use among obstetrics residents and healthcare practitioners. Electronic search of Medline, Pub Med, Health Internetwork Access to Research Initiative (HINARI) and Google Scholar databases from 1953 to 10th December 2014 was conducted for studies which compared clinical and sonographic foetal weight estimation. Various formulae have been suggested by researchers over the years. The methods however depend on the clinical dexterity of clinicians' and not on specific measurements. No simple and easily applied formula has yet been suggested to transform an external maternal measurement into an estimated foetal weight. Researchers on estimation of foetal weight should work towards a consensus and reproducible formula for clinical foetal weight estimation. Symphysio fundal height (SFH) measurement with a tape-measure seems a simple clinical method because it is cheap, readily available, non-invasive and acceptable to patients. These skills should be practiced by senior obstetricians and taught to midwifes, house officers, medical officers and obstetrics residents. It is however subjected to various degrees of intra-observer and inter-observer errors and studies comparing the different formulae are lacking. Therefore, further researches are needed to improve reliability and reproducibility of these clinical methods. The reliability of other clinical methods other than Dare' method should also be explored.

Sonographic weight estimation in fetal macrosomia: influence of the time interval between estimation and delivery

To evaluate the influence of the time interval between examination and delivery on the accuracy of sonographic weight estimation (WE) in fetal macrosomia. 896 singleton pregnancies (birth weight > 4,000 g) with a total of 1,281 sonographic weight estimations were included in this retrospective cohort study. Fetuses were divided into six groups with regard to the time interval between estimation and delivery: group 1: scan-to-delivery interval: 0 days; group 2: scan-to-delivery interval: 1-3 days; group 3: scan-to-delivery interval: 4-7 days; group 4: scan-to-delivery interval: 8-14 days; group 5: scan-to-delivery interval: 15-21 days; group 6: scan-to-delivery interval: 22-42 days. The accuracy of WE was compared between five commonly used formulas using means of percentage errors (MPE), random error, medians of absolute percentage errors (MAPE), and proportions of estimates within 10 % of actual birth weight. Significant differences were found between the time interval groups with regard to MAPE and MPE values (p < 0.001). All formulas showed a systematic underestimation of fetal weight (negative MPEs) (p < 0.05). MPE values were closest to zero in time interval group 1 and 2. From group 3 to 6, a continuous decrease was observed. The lowest MAPE was found with the Merz formula in group 1 and 2. Values increased continuously from group 3 to 6. Differences between time interval group one and three did not reach statistical significance. WE in fetal macrosomia shows the best results when examinations are performed within 7 days before delivery, using the formula of Merz et al. Accuracy significantly decreases after this time period.

527: Sonographic weight estimation of small for gestational age fetuses: is the optimal model related to fetal body proportions?

527: Sonographic weight estimation of small for gestational age fetuses: is the optimal model related to fetal body proportions?

A search for the most accurate formula for sonographic weight estimation by fetal sex - a retrospective cohort study.

The aim of this study was to assess the effect of fetal sex on the accuracy of multiple formulas for sonographic estimation fetal weight (SEFW). The cohort included all singleton live births recorded at a single medical center from January 2004 to September 2011. The accuracy of SEFW was compared between male and female fetuses using 6575 SEFW performed within 3 days prior to delivery. Fetal weight was estimated using 27 models. The accuracy of different formulas in predicting birth weight of male and female fetuses was found to be significantly different in almost every accuracy index that was compared (P < 0.05). The model by Sabbagha et al. was found to be the most accurate in assessing female fetuses. The most accurate model for male fetuses was a sex-specific formula by Melamed et al. We also found that a combination of the most accurate formula for each sex to one combined sex-specific model increased SEFW accuracy significantly. The accuracy of SEFW is significantly related to fetal sex. The combination of the formulas by Melamed et al. and Sabbagha et al. for male and female fetuses accordingly allowed more accurate SEFW in our research population.

Statistical limits in sonographic estimation of birth weight.

The accuracy of sonographic estimation of birth weight (EBW) is compromised by the precision of the biometrical measurements and the quality of the algorithms. This prospective study was to evaluate technical aspects to derive new equations for the EBW. Three consecutive phases were carried out (1) to recruit a homogenous population, (2) to derive eight new algorithms using a multiple stepwise mathematical/statistical method, and (3) to test the accuracy of the developed equations. Only those patients with a singleton pregnancy who delivered within 48h from the scan were considered for the analysis. The study population was made of 473 women. Four polynomial, two square root and two logarithmic algorithms were derived from a balanced study group of 200 women selected from the original study population. These formulas were subsequently applied and compared between them and showed a significant correlation with birth weight (p<0.0001) and satisfactory statistical performances (r>0.9), nevertheless they performed similarly to other equations previously published. The present findings define better the limitations associated with the intrinsic properties of algorithms and highlight that the possibility to improve the precision of sonographic measurements remains the only point at issue to increase the accuracy in the prediction of birth weight.