Sonographic Weight Research Articles

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.

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.

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.

Portal hypertension and hypersplenism in extrahepatic portal venous obstruction: Are they related?

Portal hypertension (PHT) due to extrahepatic portal venous obstruction (EHPVO) is common in developing countries. Hypersplenism is a near-constant feature of EHPVO, but its significance, unlike in cirrhotics, is unknown. We aimed to study the relationship between hypersplenism and the severity of PHT in patients with EHPVO. This prospective study was done at a tertiary care center from January 2014 to August 2015. All patients with EHPVO who underwent a splenectomy and a shunt or devascularization were included. Data regarding clinical profile, preoperative parameters, and intraoperative details were recorded. The correlation was studied between hypersplenism and the intraoperatively measured portal pressures and markers of PHT. Of the 40 patients studied (mean [SD] age 22.4 [8.4]years), hematological hypersplenism was present in 39 (97.5%). The mean (SD) hemoglobin, total leukocyte counts (TLC), and platelet counts were 9.9 (2.4)g/dL, 2971 (1239)cells/mm3, and 66,400 (32047)cells/mm3, respectively. The mean (SD) sonographic spleen volume (SV), splenic weight, and intraoperative portal pressure were 1084.7 (553.9)cm3, 1088.7 (454.7)g, and 35.6 (5.1)mmHg, respectively. The TLC and platelet counts correlated inversely with the portal pressure. Additionally, the platelet counts correlated negatively with eradicated variceal status, SV, and weight; hemoglobin with SV and weight; and TLC with SV. Multivariate analysis showed the platelet counts were an independent predictor of portal pressures and platelet counts ≤ 53,500cells/mm3 indicated significantly high portal pressures. The platelet counts showed a significant inverse correlation with portal pressures in patients with EHPVO and may be used as surrogate markers of PHT. A platelet count ≤ 53,500cells/mm3 is predictive of significantly high pressures.

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.

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.

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.

Clinical significance of prenatal diagnosis of macrosomia by ultrasound

Оbjective: Establish the diagnostic value of ultrasound examination in prenatal diagnosis of macrosomia among the women without diabetes and to determine its effect on birth outcomes. Мethods: This is a retrospective cohort study done at the Orenburg municipal perinatal center and maternity hospital № 2 since 2006 to 2012. In this study 3760 pregnant women were analyzed who delivered term, singleton, live born infants. The estimated fetal sonographic weight by the formula Hadlock’s was obtained within the last week prior to delivery. The study population was divided into 4 groups (true positive, true negative, false positive, false negative) according to the estimated fetal weight (EFW) and regarding the birth weight (BW). Receiver-operating characteristics (ROC) curves were generated to compare the prediction of macrosomia when using different observation methods. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated. The mean value of two groups were compared using two sample t test and χ² test for comparison of proportions. Results: In order to assess the accuracy of the ultrasound in prenatal diagnosis of macrosomia the study population was divided into 4 groups according to the estimated fetal weight (EFW) and regarding the birth weight (BW): true positive (n-147), false negative (n-229 ), false positive (n-353), true negative (n-3031). Results of the study showed no statistically significant differences between the birth weight and estimated fetal weifht by ultrasound alone only in the macrosomia group with true-positive results (p = 0.9). In applying the ROC (Receiver Operating Characteristic curve) performance analysis sensitivity and spesificity in the prediction of the macrosomia by ultrasound revealed the average predictive power of the method. Area under the curve (Area under ROC curve, AUC) made 0.7295 (95 % CI: 0.695-0.781), which corresponds to a predetermined average accuracy. The accuracy of macrosomia prediction by ultrasound methods was 90 %, sensitivity - 35 %, specificity - 93,5 %. Сesarian sections were performed for 40 % of the pregnant women, where fetal macrosomia was truly ruled in (true positive) and 16% of the women who delivered normal weight infants (true negative). Overestimation of fetal weight (false positive) has led to the 30 % rate of cesarean sections. Underestimation of fetal weight (false negative) has decreased to the 24% rate of cesarean sections but in this case perinatal complications have increased. Conclusion: Results showed an average accuracy in predicting macrosomia by the formula Hadlock’s. The results of the study have proved that the inappropriate prediction macrosomia of fetal weight has influence on the mode of delivery. Overestimation of fetal weight has led the proportion of cesarian sections. Underestimation of fetal macrosomia has increased perinatal complications.

Sonographic Weight Estimation in Small-for-Gestational-Age Fetuses.

To determine the accuracy of sonographic weight estimation (WE) for small-for-gestational-age (SGA) fetuses, and to further differentiate the evaluation between symmetric and asymmetric SGA fetuses. The accuracy of WE in SGA fetuses (n = 898) was evaluated using 14 sonographic models and was further differentiated between symmetric (n = 750) and asymmetric (n = 148) SGA fetuses. SGA fetuses were considered to be asymmetric with a head circumference to abdominal circumference ratio above the 95th percentile. The accuracy of the different formulas was compared using means of percentage errors (MPE), medians of absolute percentage errors (MAPE), and proportions of estimates within 10 % of actual birth weight. RESULTS for the subgroup of asymmetric SGA fetuses differed significantly from the subgroup of symmetric SGA fetuses. MPE values were closer to zero with most of the formulas in the asymmetric SGA group. Apart from the Siemer, Shepard, Merz and Warsof equations, all formulas showed an underestimation of fetal weight in asymmetric SGA fetuses. In contrast, in the symmetric SGA group, all of the formulas commonly used for fetuses in a normal weight range showed a systematic overestimation of fetal weight. Overall the best accuracy was achieved by using the Sabbagha equation (MPE 1.7 %; SD 9.0 %; MAPE: 6.0). An accurate WE in SGA fetuses is feasible using the Sabbagha formula. However, one has to be aware of the significant differences in WE between symmetric and asymmetric SGA fetuses.

A New Sonographic Weight Estimation Formula for Fetuses with Congenital Diaphragmatic Hernia.

The accuracy of the sonographic weight estimation (WE) of fetuses with congenital diaphragmatic hernia (CDH) is significantly lower than that of fetuses without any malformations. The objective of this study was to develop and evaluate the first specific sonographic weight formula for fetuses with CDH. In a retrospective, multicenter, cohort study, a statistical estimation technique known as "multivariable fractional polynomial regression" was applied to a group of 146 fetuses with CDH. Each fetus underwent an ultrasound examination with complete biometric parameters within 7 days of delivery. A new formula was derived using the obtained data and was then compared with other commonly used equations. The accuracy of the different formulas was compared using means of signed percentage errors (SPE), medians of absolute percentage errors (MAPE), and fractions of estimates within prespecified error bounds. The new derived formula is: EFW = 10^(4.6729 107 371 + 0.2365 011 768 * HC + 0.2228 897 682 * FL^2 - 0.0129 895 773 * FL^3 - 1.0470 039 072 * (FL * HC)^0.5 + 0.0004 314 661 * (AC * HC) - [in case of liver herniation] 0.0062 112 122), where EFW is the estimated fetal weight, HC is the head circumference, AC is the abdominal circumference, and FL is the femur length. The new formula proved to be superior to other established equations, showing both the lowest median absolute percentage error (MAE: 6.97) and mean signed percentage error (SPE: 0.40), and the best distribution of absolute percentage errors within prespecified error bounds. This new formula significantly improves weight estimation in fetuses with CDH.

Sonographic weight estimation in fetuses with breech presentation.

Sonographic weight estimation in fetuses with breech presentation.

A new formula for optimized weight estimation in extreme fetal macrosomia (≥4500 g)

Purpose: To develop and to evaluate a specific sonographic weight formula for fetuses with extreme macrosomia (≥4500 g).

IVF culture medium affects human intrauterine growth as early as the second trimester of pregnancy†

When does a difference in human intrauterine growth of singletons conceived after IVF and embryo culture in two different culture media appear? Differences in fetal development after culture of embryos in one of two IVF media were apparent as early as the second trimester of pregnancy. Abnormal fetal growth patterns are a major risk factor for the development of chronic diseases in adult life. Previously, we have shown that the medium used for culturing embryos during the first few days after fertilization significantly affects the birthweight of the resulting human singletons. The exact onset of this growth difference was unknown. In this retrospective cohort study, all 294 singleton live births after fresh embryo transfer in the period July 2003 to December 2006 were included. These embryos originated from IVF treatments that were part of a previously described clinical trial. Embryos were allocated to culture in either Vitrolife or Cook commercially available sequential culture media. We analysed ultrasound examinations at 8 (n = 290), 12 (n = 83) and 20 weeks' (n = 206) gestation and used first-trimester serum markers [pregnancy-associated plasma protein-A (PAPP-A) and free β-hCG]. Differences between study groups were tested by the Student's t-test, χ(2) test or Fisher's exact test, and linear multivariable regression analysis to adjust for possible confounders (for example, parity, gestational age at the time of ultrasound and fetal gender). A total of 294 singleton pregnancies (Vitrolife group nVL = 168, Cook group: nC = 126) from 294 couples were included. At 8 weeks' gestation, there was no difference between crown-rump length-based and ovum retrieval-based gestational age (ΔGA) (nVL = 163, nC = 122, adjusted mean difference, -0.04 days, P = 0.84). A total of 83 women underwent first-trimester screening at 12 weeks' gestation (nVL = 45, nC = 38). ΔGA, nuchal translucency (multiples of median, MoM) and PAPP-A (MoM) did not differ between the study groups. Free β-hCG (MoM) ± SEM differed significantly (1.55 ± 0.19 in Vitrolife versus 1.06 ± 0.10 in Cook; P = 0.031, Student's t-test). At 20 weeks' gestation, a more advanced GA, reflecting an increased fetal growth, was seen at ultrasound examination in the Vitrolife group (n = 115) when compared with the Cook group (n = 91). After adjustment for confounding factors, both the difference between GA based on three biparietal diameter dating formulas minus the actual (ovum retrieval based) GA (adjusted mean difference + 1.14 days (P = 0.04), +1.14 days (P = 0.04) and +1.36 days (P = 0.048)), as well as head circumference (HC) and trans-cerebellar diameter (TCD) were significantly higher in the Vitrolife group (HCvl 177.3 mm, HCc 175.9 mm, adjusted mean difference 1.8, P = 0.03; TCDvl 20.5 mm, TCDc 20.2 mm, adjusted mean difference 0.4, P = 0.008). A first trimester (12 weeks) fetal screening was not yet offered routinely during the study period, therefore only 28% of women in our study participated in this elective screening programme. Although all sonographers were experienced and specially trained to perform these ultrasound examinations and were unaware of the randomization procedure, we cannot totally rule out possible intra- and inter-observer variability. Despite being indispensable in daily practice, sonographic weight formulas have a limited accuracy. According to the fetal origins hypothesis, many adult diseases originate in utero owing to adaptations made by the fetus to the environment it encounters. This study indicates that the embryonic environment is already important for fetal development. Therefore, our study emphasizes the need to investigate fetal growth patterns after assisted reproduction technologies and long-term health outcomes of IVF children, especially in relation to the culture medium used during the first few days of preimplantation development. Not applicable.

Assessment of the Accuracy of Multiple Sonographic Fetal Weight Estimation Formulas: A 10-Year Experience From a Single Center

The primary aim of this study was to compare the accuracy of sonographic fetal weight estimation models. The secondary aim was to define the most accurate time (4-7 or 3 days before delivery) for evaluating fetal weight. In this retrospective cohort study, a total of 12,798 sonographic fetal weight estimations were analyzed, of which 9459 were performed within 3 days of delivery and 3339 within 4 to 7 days. The cohort included all singleton pregnancies recorded at a single medical center from January 2000 to December 2010, with 24 weeks' gestation minimum. Predicted birth weights were calculated according to 23 sonographic fetal weight estimation models; in total, 294,354 sonographic weight estimations were evaluated and compared to the actual birth weights. The accuracy of the models in predicting birth weight differed considerably. The most accurate models used 3 or more fetal measurements followed by models using abdominal circumference only. The models developed by Sabbagha et al (Am J Obstet Gynecol 1989; 160:854-862) proved most accurate, with a mean percent error of -0.2% and greater than 92% of estimates within 15% of birth weight (P < .05). Nineteen sonographic fetal weight estimation models (82.6%) better predicted fetal weight at 4 to 7 days before delivery (P < .001). Twenty-two (95%) of the models were less accurate at the extreme ends of fetal weight. Different formulas for fetal weight estimation vary greatly; we recommend that each center should evaluate the most accurate formula according to its attending population. Estimation of fetal weight performed 4 to 7 days before delivery using most models was more accurate than estimations performed 3 days before delivery.