Sonographic fetal weight estimation in normal and overweight/obese healthy term pregnant women by gestation-adjusted projection (GAP) method

Pre-delivery BMI and the Accuracy of Fetal Weight Estimation in Very Preterm Infants

OBJECTIVES

To examine the relation between maternal pre-delivery BMI and the accuracy of sonographic estimated fetal weight (EFW) in very preterm infants (<32 weeks gestation).

METHODS

This retrospective study included singleton infants born between January 2010 and March 2023, at gestational ages 230 to 316 weeks, at a tertiary university-affiliated hospital. Absolute weight, percentage error, absolute percentage error, and overestimation and underestimation of EFW were compared between women with pre-delivery normal weight (BMI 18.5-24.99 kg/m2), overweight (BMI 25.0-29.99 kg/m2), and obesity (BMI >35.0 kg/m2). Multivariate linear regression analyses adjusted for potential confounders were performed to assess relations of maternal pre-conception and of pre-delivery BMI, with EFW accuracy.

RESULTS

Included were 286 pregnancies. The absolute difference, percentage error, absolute percentage error, error within the 10% range, and underestimation or overestimation of EFW were similar between the groups. The multivariate linear regression analyses did not show significant associations of pre-conceptional BMI or of pre-delivery BMI with the percentage error. However, for small for gestational age compared to appropriate for gestational age fetuses, the percentage error was greater (8.9% vs. -0.6%, β = 0.35, P < 0.001) and the absolute percentage error was greater (11.0% vs. 6.7%, P < 0.001). Small for gestational age fetuses were at risk of fetal weight overestimation (percentage error exceeding 15%); OR 7.20 (95% CI 2.91-17.80).

CONCLUSIONS

Maternal pre-delivery BMI was not found to be related to EFW accuracy in very preterm infants. Nevertheless, EFW should be interpreted carefully, as it may underdiagnose poor fetal growth in this population.

Impact of maternal body mass index on the accuracy of third trimester sonographic estimation of fetal weight

OBJECTIVES

To Determine whether maternal body mass index (BMI) can affect the accuracy of sonographic estimation of fetal weight (EFW) in the third trimester when compared to neonatal birthweight (BW).

METHODS

Secondary analysis from our original prospective cohort of pregnant women beyond 34 weeks, distributed in 4 groups according to their BMI: normal, overweight, obese and morbid obese. Fetal biometry and fluid measurements were obtained by two experienced sonographers, blinded for patient's clinical information and to each other's measurements. Average EFW and neonatal BW were converted into gestational-specific Z-scores. Interobserver correlation coefficient (ICC) and Cronbach's reliability coefficient (CRC) were calculated. Bland-Altman (BA) plots were constructed to assess the level of accuracy.

RESULTS

100 women were enrolled (800 measurements obtained by 17 sonographers): 17 had normal BMI (17%), 27 were overweight (27%), 29 were obese (29%) and 27 were morbidly obese (27%). There was no statistical difference for GA at delivery (p = 0.74), EFW (p = 0.05) or BW (p = 0.09) between groups (Table 1). Mean Z-score for EFW was - 0.17 (SD 0.81) and for neonatal BW was - 0.25 (SD 0.74). ICC was 0.69 (95% CI 0.57, 0.78) and CRC was 0.82. Mean Z-score difference was small (Table 2). When stratifying according to BMI categories, the ICC ranged from 0.49 to 0.76. Reliability indices ranged from 0.66 to 0.86. The Z-scores' differences were overall small with no statistical difference (Table 3). BA showed evenly distributed interobserver differences (Fig. 1).

CONCLUSIONS

When performed by trained sonographers, fetal weight estimation in the third trimester is accurate when compared to neonatal birthweight at increasing BMI categories.

The birth weight of macrosomia influence the accuracy of ultrasound estimation of fetal weight at term

OBJECTIVE

To evaluate and analyze the accuracy of ultrasound estimation of the fetal weight of Macrosomia at term.

METHOD

The instruments used were α6(Aloka; Japan) color Doppler ultrasound imagers, and vinno 80 (feieno; China) with a frequency of 3.5 MHz. The formula used to calculate the estimated fetal birth weight (EFW) was that proposed by Hadlock et al. (Hadlock 2). The biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) measurements were performed strictly following the practice guidelines. Detailed measurement standards are shown in the figure and the table in the text. Macrosomia is typically defined as a birth weight above the 90th percentile for gestational age or >4000 g.Two indexes were used to calculate the error between EFW and birth weight (BW): Simple error (SE = BW - EFW); Absolute percentage error (APE, which reflects this percentage in absolute value, percentage error [PE = SE/BW] × 100). In order to better evaluate the measurement results, we made the following definitions: 1. When APE > 15%, the measurement deviation is significant. 2. The ratio of those cases with APE > 15% to the total number of cases measured by a sonographer was greater than 20%, indicating that the sonographer was prone to significant measurement deviation.

RESULT

A total of 374 cases were analyzed. The mean maternal age was 31.48 (±15.93) years. Each pregnant woman carries only one fetus. The mean gestational age at delivery was 39.93 (±0.84) weeks. There were 245 male infants (65.5%), 129 female infants (34.5%), 214 cesarean section (57.2%), and 160 vaginal delivery (42.7%). 339 cases (90.64%) were estimated to be lower than the actual BW. The estimated weight was higher than the actual weight in 35 cases, accounting for 9.36%.The APE>15% in 56 cases, accounting for 14.97%. The accuracy of estimated fetal weight was closely related to the BW of the fetus and had no significant correlation with the seniority of the physician, the gender of the fetus, and the fetal position.

CONCLUSION

Studies on macrosomia have shown that the BW of macrosomia tends to be underestimated, which is also reflected in the results of this study. The accuracy of estimated fetal weight still needs to be improved. Our study found that the accuracy of estimated fetal weight was closely related to the BW of the fetus and had no significant correlation with the seniority of the physician, the gender of the fetus, and the fetal position. The correlation between the section and calculation formula on the measurement accuracy needs to be studied. Through systematic data analysis, we can find the doctors whose measurements are relatively inaccurate in our department and carry out targeted quality control to improve the measurement accuracy.

Influence of maternal body mass index on interobserver variability of fetal ultrasound biometry and amniotic-fluid assessment in late pregnancy

OBJECTIVE

To determine the interobserver reproducibility of fetal ultrasound biometric and amniotic-fluid measurements in the third trimester of pregnancy, according to maternal body mass index (BMI) category.

METHODS

This was a prospective cohort study of women with a singleton gestation beyond 34 weeks, recruited into four groups according to BMI category: normal (18.0-24.9 kg/m² ), overweight (25.0-29.9 kg/m²⁾ , obese (30.0-39.9 kg/m² ) and morbidly obese (≥ 40 kg/m² ). Multiple pregnancies, women with diabetes and pregnancies with a fetal growth, structural or genetic abnormality were excluded. In each woman, fetal biometric (biparietal diameter (BPD), head circumference, abdominal circumference (AC), femur length (FL) and estimated fetal weight) and amniotic-fluid (amniotic-fluid index (AFI) and maximum vertical pocket (MVP)) measurements were obtained by two experienced sonographers or physicians, blinded to gestational age and each other's measurements. Differences in measurements between observers were expressed as gestational age-specific Z-scores. The interobserver intraclass correlation coefficient (ICC) and Cronbach's reliability coefficient (CRC) were calculated. Bland-Altman analysis was used to assess the degree of reproducibility.

RESULTS

In total, 110 women were enrolled prospectively (including 1320 measurements obtained by 17 sonographers or physicians). Twenty (18.2%) women had normal BMI, 30 (27.3%) women were overweight, 30 (27.3%) women were obese and 30 (27.3%) women were morbidly obese. Except for AFI (ICC, 0.65; CRC, 0.78) and MVP (ICC, 0.49; CRC, 0.66), all parameters had a very high level of interobserver reproducibility (ICC, 0.72-0.87; CRC, 0.84-0.93). When assessing reproducibility according to BMI category, BPD measurements had a very high level of reproducibility (ICC ≥ 0.85; CRC > 0.90) in all groups. The reproducibility of AC and FL measurements increased with increasing BMI, while the reproducibility of MVP measurements decreased. Among the biometric parameters, the difference between the BMI categories in measurement-difference Z-score was significant only for FL. Interobserver differences for biometric measurements fell within the 95% limits of agreement.

CONCLUSION

Obesity does not seem to impact negatively on the reproducibility of ultrasound measurements of fetal biometric parameters when undertaken by experienced sonographers or physicians who commonly assess overweight, obese and morbidly obese women. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Obesity and Gestational Diabetes in Pregnant Care and Clinical Practice

Obesity and Gestational Diabetes Mellitus (GDM) are the most frequent pathologies affecting mothers and offspring during pregnancy. Both conditions have shown a sustained increase in their prevalence in recent years, and they worsen the outcome of pregnancy and the long-term health of mothers. Obesity increases the risk of GDM and pre-eclampsia during pregnancy and elevates the risk of developing metabolic syndrome in later life. Offspring of obese mothers have an increased risk of obstetric morbidity and mortality and, consistent with the developmental origins of health and disease, a long term risk of childhood obesity and metabolic dysfunction. On the other hand, GDM also increases the risk of pre-eclampsia, caesarean section, and up to 50% of women will develop type 2 diabetes later in life. From a fetal point of view, it increases the risk of macrosomia, large-for-gestational-age fetuses, shoulder dystocia and birth trauma. The insulin resistance and inflammatory mediators released by a hypoxic trophoblast are mainly responsible for the poor pregnancy outcome in obese or GDM patients. The adequate management of both pathologies includes modifications in the diet and physical activity. Drug therapy should be considered when medical nutrition therapy and moderate physical activity fail to achieve treatment goals. The antenatal prediction of macrosomia is a challenge for physicians. The timing and the route of delivery should consider adequate metabolic control, gestational age, and optimal conditions for a vaginal birth. The best management of these pathologies includes pre-conception planning to reduce the risks during pregnancy and improve the quality of life of these patients.

Observer Influence with Other Variables on the Accuracy of Ultrasound Estimation of Fetal Weight at Term

Background and Objectives: The accuracy with which the estimation of fetal weight (EFW) at term is determined is useful in order to address obstetric complications, since it is a parameter that represents an important prognostic factor for perinatal and maternal morbidity and mortality. The aim of this study was to determine the role of the experienced observers with other variables that could influence the accuracy of the ultrasound used to calculate EFW at term, carried out within a period of seven days prior to delivery, in order to assess interobserver variability. Materials and Methods: A cross-sectional study was performed including 1144 pregnancies at term. The validity of the ultrasound used to calculate EFW at term was analyzed using simple error, absolute error, percentage error and absolute percentage error, as well as the percentage of predictions with an error less than 10 and 15% in relation to maternal, obstetric and ultrasound variables. Results: Valid predictions with an error less than 10 and 15% were 74.7 and 89.7% respectively, with such precision decreasing according to the observer as well as in extreme fetal weights. The remaining variables were not significant in ultrasound EFW at term. The simple error, absolute error, percentage error and absolute percentage error were greater in cases of extreme fetal weights, with a tendency to overestimate the low weights and underestimate the high weights. Conclusions: The accuracy of EFW with ultrasound carried out within seven days prior to birth is not affected by maternal or obstetric variables, or by the time interval between the ultrasound and delivery. However, accuracy was reduced by the observers and in extreme fetal weights.

Guideline No. 392-Pregnancy and Maternal Obesity Part 2: Team Planning for Delivery and Postpartum Care

OBJECTIVE

This guideline will review key aspects in the pregnancy care of women with obesity. Part I will focus on Preconception and Pregnancy Care. Part II will focus on Team Planning for Delivery and Postpartum Care.

INTENDED USERS

All health care providers (obstetricians, family doctors, midwives, nurses, anaesthesiologists) who provide pregnancy-related care to women with obesity.

TARGET POPULATION

Women with obesity who are pregnant or planning pregnancies.

EVIDENCE

Literature was retrieved through searches of Statistics Canada, Medline, and The Cochrane Library on the impact of obesity in pregnancy on antepartum and intrapartum care, maternal morbidity and mortality, obstetric anaesthesia, and perinatal morbidity and mortality. Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to September 2018. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the authors. Then the Maternal-Fetal Medicine Committees peer reviewed the content and submitted comments for consideration, and the Board of the Society of Obstetricians and Gynaecologists of Canada (SOGC) approved the final draft for publication. Areas of disagreement were discussed during meetings at which time consensus was reached. The level of evidence and quality of the recommendation made were described using the Evaluation of Evidence criteria of the Canadian Task Force on Preventive Health Care.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in these guidelines may increase obstetrical provider recognition of the issues affecting pregnant individuals with obesity, including clinical prevention strategies, communication between the health care team, the patient and family as well as equipment and human resource planning. It is hoped that regional, provincial and federal agencies will assist in the education and support of coordinated care for pregnant individuals with obesity.

GUIDELINE UPDATE

SOGC guideline will be automatically reviewed 5 years after publication. However, authors can propose another review date if they feel that 5 years is too short/long based on their expert knowledge of the subject matter.

SPONSORS

This guideline was developed with resources funded by the SOGC.

SUMMARY STATEMENTS

RECOMMENDATIONS.

THIRD TRIMESTER ULTRASOUND SCAN COMBINED WITH A CLINICAL METHOD FOR ACCURATE BIRTHWEIGHT PREDICTION AT TERM: A COHORT STUDY IN SPAIN

OBJECTIVE

To develop and assess an equation based on maternal clinical parameters and third trimester ultrasound biometry (combined method), and compare it with ultrasound-estimated foetal weight (EFW) calculated using the Hadlock 2 formula.

METHODS

Cohort study. A total of 1,224 women with singleton pregnancies who had undergone foetal ultrasound scanning (USS) at 34 weeks were recruited. The study was conducted at a reference center in Valencia (Spain) between January and December 2016. A gestation-adjusted projection (GAP) method was applied to estimated foetal-weight-for-gestational-age by foetal gender at delivery (EFWa). A multivariate regression was created to estimate foetal weight at term (EFWmr) using anthropometric, demographic, ultrasonographic and obstetric-neonatal variables. EFWa and EFWmr were calculated and compared with actual birthweight.

RESULTS

The proportion for EFWmr within <10% of actual birthweight was greater than EFWa (82% vs. 65%, p<0.001). The mean relative error in foetal-weight predictions by using EFWmr was reduced from 6.7% to 0.9% (difference 5.7% 95% CI: 5.4 to 6.0) paired t-test p<0.001, significantly improving the accuracy attainable with USS. The EFWmr outperformed the GAP method in predicting birthweight, within 1% relative error. For new- borns <2,500 g, the proportion of estimates within <10% of the actual birthweight for the EFWmr was greater than that of the EFWa (20.4 vs. 16.3%, p=0.005). For babies with normal birthweight (2,500-3,999 g), EFWmr was a better predictor of birthweight than EFWa (84.5 vs. 65.7%, p<0.001).

CONCLUSIONS

Mathematical modelling to predict birthweight improves third trimester routine ultrasound measurement to estimate neonatal weight at term.

Directive clinique No 392 - Grossesse et obésité maternelle Partie 2 : Planification en équipe de l'accouchement et soins post-partum

OBJECTIF

La présente directive clinique aborde les aspects essentiels des soins prénataux chez les femmes atteintes d'obésité. La partie 1 porte sur la préconception et les soins prénataux. La partie 2 porte sur la planification en équipe de l'accouchement et les soins post-partum. UTILISATEURS CONCERNéS: Tous les fournisseurs de soins de santé (obstétriciens, médecins de famille, sages-femmes, infirmières, anesthésiologistes) qui prodiguent des soins relatifs à la grossesse auprès de femmes atteintes d'obésité.

POPULATION CIBLE

Femmes atteintes d'obésité qui sont enceintes ou prévoient le devenir. DONNéES PROBANTES: Des recherches ont été menées en consultant les ressources de Statistique Canada, de Medline et de Cochrane Library en vue d'en tirer la littérature relativement aux effets de l'obésité durant la grossesse sur les soins prénataux et intrapartum, la morbidité et la mortalité maternelles, l'anesthésie obstétricale ainsi que sur la morbidité et la mortalité périnatales. Seuls les résultats de revues systématiques, d'essais cliniques randomisés ou comparatifs et d'études observationnelles ont été retenus. Aucune restriction de date ou de langue n'a été employée. Les recherches ont été mises à jour régulièrement, et les résultats ont été incorporés à la directive clinique jusqu'en septembre 2018. Nous avons également tenu compte de la littérature grise (non publiée) obtenue sur les sites Web d'organismes d'évaluation des technologies de la santé et d'autres organismes pertinents, dans des collections de directives cliniques et des registres d'essais cliniques, et auprès d'associations nationales et internationales de médecins spécialistes. MéTHODES DE VALIDATION: Le contenu et les recommandations ont été rédigés et acceptés par les auteurs. Les membres du comité de médecine fœto-maternelle ont ensuite passé en revue le contenu et formulé des commentaires aux fins d'examen. Enfin, le conseil d'administration de la Société des obstétriciens et gynécologues du Canada (SOGC) a approuvé la publication de la version définitive de la directive. Les points de désaccord ont été abordés lors de réunions pour enfin arriver à un consensus. La qualité des données et des recommandations a été déterminée à l'aide des critères d'évaluation décrits par le Groupe d'étude canadien sur les soins de santé préventifs. AVANTAGES, PRéJUDICE ET COûTS: La mise en place des recommandations des présentes directives peut améliorer la reconnaissance des fournisseurs de soins obstétricaux relativement aux problèmes qui touchent les personnes enceintes atteintes d'obésité, notamment au moyen de stratégies de prévention clinique; de la communication entre l'équipe de soins de santé, la patiente et la famille; et de la planification de l'équipement et des ressources humaines. Il est à espérer que les organismes régionaux, provinciaux et fédéraux participeront à la formation et au soutien en matière de soins coordonnés pour les personnes enceintes atteintes d'obésité. MISE à JOUR DE LA DIRECTIVE CLINIQUE: Les directives de la SOGC sont automatiquement passées en revue 5 ans après leur publication. Les auteurs peuvent toutefois proposer une autre date de réévaluation s'ils croient qu'une période de 5 ans est trop courte ou trop longue en fonction de leurs connaissances du sujet à titre d'experts en la matière.

PROMOTEURS

La présente directive a été élaborée à l'aide de ressources financées par la SOGC. DéCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Correlation of Ultrasonographic Estimation of Fetal Weight with Actual Birth Weight as Seen in a Private Specialist Hospital in South East Nigeria

Background

Ultrasound estimation of fetal weight at term provides vital information for the skilled birth attendants to make decisions on the possible best route of delivery of the fetus. This is more pertinent in a setting where women book late for antenatal care.

Aim and Objectives

The study evaluated the accuracy of estimation of fetal weight with ultrasound machine at term.

Methods

This was a cross sectional study conducted at a private specialist hospital in Nigeria. A coded questionnaire was used to retrieve relevant information which included the last menstrual period, gestational age, parity, and birth weight. Other information obtained includes Ultrasound-delivery interval, maternal weight, and route of delivery. The ultrasound was used to estimate the fetal weight. The actual birth weight was determined using a digital baby weighing scale. The data were inputted into Microsoft excel and analyzed using STATA version 14. Statistical significance was considered at p-values less than 0.05. Measures of accuracy evaluated in the statistical analysis included mean error, mean absolute error, mean percentage error, and mean absolute percentage error. Pearson correlation was done between the estimated ultrasound fetal weight and the actual birth weight. The proportion of estimates within ±10% of actual birth weight was also determined.

Result

A total of 170 pregnant women participated in the study. The mean maternal age was 30.77 years ± 5.54. The mean birth weight was 3.47 kg ± 0.47, while the mean estimated ultrasound weight was 3.43 kg ± 0.8. There was positive correlation between the ultrasound estimated weight and the actual birth weight. The mean ultrasound scan to delivery interval was 0.8 days (with range of 0–2 days). The study recorded a mean error of estimation of 41.17 grams and mean absolute error of 258.22 grams. The mean percentage error was 0.65%, while the mean absolute error of estimation was 7.56%. About 72.54% of the estimated weights were within 10% of the actual birth weight.

Conclusion

The ultrasound estimated fetal weight correlated with the actual birth weight. Ultrasound estimation of fetal weight should be done when indicated to aid the clinician in making decisions concerning routes of delivery.

Fetal weight estimation at term - ultrasound versus clinical examination with Leopold's manoeuvres: a prospective blinded observational study

BACKGROUND

Fetal weight estimation is of key importance in the decision-making process for obstetric planning and management. The literature is inconsistent on the accuracy of measurements with either ultrasound or clinical examination, known as Leopold's manoeuvres, shortly before term. Maternal BMI is a confounding factor because it is associated with both the fetal weight and the accuracy of fetal weight estimation. The aim of our study was to compare the accuracy of fetal weight estimation performed with ultrasound and with clinical examination with respect to BMI.

METHODS

In this prospective blinded observational study we investigated the accuracy of clinical examination as compared to ultrasound measurement in fetal weight estimation, taking the actual birth weight as the gold standard. In a cohort of all consecutive patients who presented in our department from January 2016 to May 2017 to register for delivery at ≥37 weeks, examination was done by ultrasound and Leopold's manoeuvres to estimate fetal weight. All examiners (midwives and physicians) had about the same level of professional experience. The primary aim was to compare overall absolute error, overall absolute percent error, absolute percent error > 10% and absolute percent error > 20% for weight estimation by ultrasound and by means of Leopold's manoeuvres versus the actual birth weight as the given gold standard, namely separately for normal weight and for overweight pregnant women.

RESULTS

Five hundred forty-three patients were included in the data analysis. The accuracy of fetal weight estimation was significantly better with ultrasound than with Leopold's manoeuvres in all absolute error calculations made in overweight pregnant women. For all error calculations performed in normal weight pregnant women, no statistically significant difference was seen in the accuracy of fetal weight estimation between ultrasound and Leopold's manoeuvres.

CONCLUSIONS

Data from our prospective blinded observational study show a significantly better accuracy of ultrasound for fetal weight estimation in overweight pregnant women only as compared to Leopold's manoeuvres with a significant difference in absolute error. We did not observe significantly better accuracy of ultrasound as compared to Leopold's manoeuvres in normal weight women. Further research is needed to analyse the situation in normal weight women.

Influence of maternal obesity on the accuracy of ultrasonography birth weight prediction

Objective: The aim of the study was to investigate whether the accuracy of ultrasound estimates of fetal weight (EFW) was dependent on maternal obesity.Study design: A prospective cross-sectional study of 1064 singleton pregnant women classified according to body mass index (BMI) into two categories: normal (BMI < 25 kg/m², n = 863) and obese (BMI ≥ 35 kg/m², n = 201) was conducted. EFW were calculated using Hadlock's formula, and the difference between EFW and the actual birthweight (absolute percent error) was analyzed in both groups. Spearman's correlation was used to assess the relationship between ultrasound performance (absolute error), maternal BMI, and actual birth weight.Results: Median absolute error of sonographic EFW was 5.90 and 6.47% for the normal and obese groups, respectively (p .38). A correlation between EFW and birth weight (BW) was found in both groups, r = 0.755 (p < .001) and r = 0.753 (p < .001), respectively. The correlation between absolute error, maternal BMI, and fetal birth weight was poor.Conclusions: Maternal obesity is unrelated to the accuracy of sonographic EFW, and regardless of maternal or fetal size, ultrasound is currently an accurate method of prediction for both obese and normal weight pregnant women.

Perinatal loss at term: role of uteroplacental and fetal Doppler assessment

OBJECTIVE

To examine the associations of uterine artery (UtA) Doppler indices and cerebroplacental ratio (CPR) with perinatal outcome at term.

METHODS

This was a retrospective cohort study conducted at a tertiary referral center that included all singleton pregnancies undergoing ultrasound assessment in the third trimester that subsequently delivered at term. Fetal biometry and Doppler assessment, including that of the umbilical artery (UA), fetal middle cerebral artery (MCA) and UtA, were recorded. Data were corrected for gestational age, and CPR was calculated as the ratio of MCA pulsatility index (PI) to UA-PI. Logistic regression analysis was conducted to examine for independent predictors of adverse perinatal outcome.

RESULTS

The study included 7013 pregnancies, 12 of which were complicated by perinatal death. When compared with pregnancies resulting in perinatal survival, pregnancies complicated by perinatal death had a significantly higher proportion of small-for-gestational-age infants (25.0% vs 5%; P = 0.001) and a higher incidence of low (< 5^th centile) CPR (16.7% vs 4.5%; P = 0.041). A subgroup analysis comparing 1527 low-risk pregnancies that resulted in fetal survival with pregnancies complicated by perinatal death demonstrated that UtA-PI multiples of the median (MoM), CPR < 5^th centile and estimated fetal weight (EFW) centile were all associated significantly with the risk of perinatal death at term (all P < 0.05). After adjusting for confounding variables, only EFW centile (odds ratio (OR) 0.96 (95% CI, 0.93-0.99); P = 0.003) and UtA-PI MoM (OR 13.10 (95%CI, 1.95-87.89); P = 0.008) remained independent predictors of perinatal death in the low-risk cohort.

CONCLUSION

High UtA-PI at term is associated independently with an increased risk of adverse perinatal outcome, regardless of fetal size. These results suggest that perinatal mortality at term is related not only to EFW and fetal redistribution (CPR), but also to indices of uterine perfusion. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Can we improve the gestation-adjusted projection (GAP) method for prediction of birth weight in morbidly obese women?. J Matern Fetal Neonatal Med 2018;32:3600-3605. [PMID: 29681190 DOI: 10.1080/14767058.2018.1468882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Objective: The gestation-adjusted projection (GAP) is a method to predict birthweight using population birth data and third trimester ultrasound fetal weight. This method usually utilizes population birth weight data from almost 40 years ago. In 2011, a large cohort of racially diverse infants across the US was included to validate updated birth curves. Our objective was to determine if the updated data would improve the accuracy of the GAP method during the third trimester among obese women. Methods: This secondary analysis of a cohort study included singleton pregnancies of obese women who had fetal growth assessment(s) in the third trimester. The first subgroup (N = 235) included women with a BMI >40 kg/m² who had ultrasounds during 30 + 0-35 + 0 weeks (EARLY) and greater than 35 + 0 weeks (LATE). The second subgroup (N = 431) included women with a BMI 30-35, 40-50, or >50 kg/m² who had an ultrasound during 34 + 0-36 + 6 weeks. Mean absolute percent error was calculated for all GAP methods and compared using paired t-tests. Sensitivity, specificity, and area under the curve for diagnosis of birth weight >4000 grams were also estimated for each GAP method. Results: The mean absolute percent error for the first subgroup (N = 235) using historical population birth weights was 7.4-7.9%. After using updated population birth weight curves using all neonates, the mean absolute percent error for the first subgroup ranged between 7.6 and 9.4%. GAP predictions using all neonates, as well as male and female-specific birth data compared to the historical population data during both the EARLY and LATE periods were significantly worse (p < .01). The mean absolute percent error for the second subgroup (N = 431) using historical population birth weights ranged from 7.2 to 7.9%. The absolute percent error using gender-specific compared to historical data was significant in the BMI 30-35 group (male 8.1% versus historical 7.6%, p < .01, female 8.1% versus historical 7.6%, p < .01). The differences in absolute percent error between historical and updated population data became less evident in the BMI 40-50 and >50-kg/m² groups (p = .05 and p = .15, respectively) though still overall performed worse with the updated data. Conclusions: Prediction of birth weight using the GAP method does not seem to be improved among obese women after using updated population data. Alternatively, modeling techniques may need to be applied to improve the accuracy of the GAP method.

Accuracy of immediate antepartum ultrasound estimated fetal weight and its impact on mode of delivery and outcome - a cohort analysis

Background

The aim of the study was to investigate the accuracy of ultrasound-derived estimated fetal weight (EFW) and to determine its impact on management and outcome of delivery.

Methods

In this single-center cohort analysis, women with a singleton term pregnancy in the beginning stages of labor were included. Women with immediately antepartum EFW (N = 492) were compared to women without ultrasound (N = 515).

Results

EFW was correct (deviation from birth weight ≤ 10%) in 72.2% (355/492) of patients with fetal biometry; 19.7% (97/492) were underestimated, and 8.1% (40/492) were overestimated. Newborns with a lower birth weight were more frequently overestimated, and newborns with higher birth weight were more frequently underestimated. The mean difference between EFW and real birth weight was − 114.5 g (standard deviation ±313 g, 95% confidence interval 87.1–142.0). The rate of non-reassuring fetal heart tracing (9.8% vs. 1.9%, P < 0.001) and of caesarean delivery (9.1% vs. 5.0%, P = 0.013) was higher in women with EFW. Overestimation was associated with an increased risk for delivery by caesarean section (odds ratio 2.80; 95% confidence interval 1.2–6.5, P = 0.017). After adjustment, EFW remained associated with increased non-reassuring fetal heart tracing (odds ratio 4.73; 95% confidence interval 2.3–9.6) and caesarean delivery (odds ratio 1.86; 95% confidence interval 1.1–3.1). The incidence of perineal tears of grade 3/4, shoulder dystocia, postnatal depression and neonatal acidosis did not differ between groups.

Conclusions

Antepartum ultrasound-derived EFW does not improve maternal and fetal outcome and is therefore not recommended.

Does Maternal Body Mass Index Have an Effect on the Accuracy of Ultrasound-Derived Estimated Birth Weight?: A Retrospective Study

OBJECTIVES

The purpose of this study was to investigate the relationship between the maternal body mass index (BMI) and the accuracy of ultrasound-derived birth weight.

METHODS

A retrospective chart review was performed on women who had an ultrasound examination between 36 and 43 weeks' gestation and had complete delivery data available through electronic medical records. The ultrasound-derived fetal weight was adjusted by 30 g per day of gestation that elapsed between the ultrasound examination and delivery to arrive at the predicted birth weight.

RESULTS

A total of 403 pregnant women met inclusion criteria. Age ranged from 13-44 years (mean ± SD, 28.38 ± 5.97 years). The mean BMI was 32.62 ± 8.59 kg/m² . Most of the women did not have diabetes (n = 300 [74.0%]). The sample was primarily white (n = 165 [40.9%]) and Hispanic (n = 147 [36.5%]). The predicted weight of neonates at delivery (3677.07 ± 540.51 g) was higher than the actual birth weight (3335.92 ± 585.46 g). Based on regression analyses, as the BMI increased, so did the predicted weight (P < .01) and weight at delivery (P < .01). The accuracy of the estimated ultrasound-derived birth weight was not predicted by the maternal BMI (P = .22). Maternal race and diabetes status were not associated with the accuracy of ultrasound in predicting birth weight.

CONCLUSIONS

Both predicted and actual birth weight increased as the BMI increased. However, the BMI did not affect the accuracy of the estimated ultrasound-derived birth weight. Maternal race and diabetes status did not influence the accuracy of the ultrasound-derived predicted birth weight.

Clinical management of pregnancy in the obese mother: before conception, during pregnancy, and post partum

The global epidemic of obesity has led to an increasing number of obese women of reproductive age. Obesity is associated with reduced fertility, and pregnancies complicated by maternal obesity are associated with adverse outcomes, including increased risk of gestational diabetes, pre-eclampsia, preterm birth, instrumental and caesarean births, infections, and post-partum haemorrhage. The medical and obstetric management of obese women is focused on identifying, addressing, and preventing some of these associated complications, and is a daunting challenge given the high percentage of patients with obesity and few therapeutic options proven to improve outcomes in this population. The UK's National Institute for Health and Care Excellence guidelines and the American College of Obstetricians and Gynecologists recommend that all pregnant women follow a healthy diet, and consider at least half an hour of moderate physical activity per day during pregnancy. However, although obese women are often directed to seek the advice of a nutritionist and to limit gestational weight gain, guidelines for the management of pregnancy and delivery in this high-risk group are lacking. The post-partum period represents an important opportunity to optimise maternal health before the next pregnancy. As many of the physiological changes of pregnancy associated with maternal obesity are present from early pregnancy onward, reducing maternal obesity before conception is probably the best strategy to decrease the health burden associated with maternal obesity.