How to calculate the fetal weight percentile? It's easier than you think! Find your baby's gestational age on the bottom of the page: draw a vertical line starting from that point. Find its weight on the left or right edge of the chart, and draw a horizontal line beginning from that point.
Mark the crossing of these two lines with a dot. Check which fetal weight percentile line on the chart is located the closest to the dot you've just drawn.
Always consult your doctor , and double check any measurements that may have any impact on clinical practice. Gestational age. Abdominal Circumference. Head Circumference. Biparietal Diameter.
Femur Length. Estimated fetal weight. Your baby is in the 50th percentile! Y axis: fetal weight in grams g. Very small and very large babies have higher mortality and morbidity rates than infants of normal size [53]. Because early detection of growth abnormalities may help to prevent fetal demise and manage perinatal complications more appropriately , monitoring of fetal growth is an important part of antepartum care.
Symphysis fundal height also known as the fundal height Measurement of the symphysis-fundal height SFH is a common screening method used to estimate the gestational age and fetal growth after 24 weeks gestation. Gestational Age weeks EFW 90th Percentile grams EFW 97th Percentile grams White Black Hispanic Asian White Black Hispanic Asian 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Sparks TN, et. J Matern Fetal Neonatal Med.
Epub Sep PMID: 3. Robert Peter J, et. Cochrane Database Syst Rev. PMID: 07 5. PMID: 7. Fetal growth restriction. Practice Bulletin No. American College of Obstetricians and Gynecologists. Unterscheider J, et.
Am J Obstet Gynecol. A classification system for selective intrauterine growth restriction in monochorionic pregnancies according to umbilical artery Doppler flow in the smaller twin.
Ultrasound Obstet Gynecol. PMID: Ben-Haroush A,et. PMID Hadlock FP, et. Am J Obstet Gynecol , Hadlock FP. Radiol Clin North Am. Sonographic evaluation of intrauterine growth retardation.
Hadlock FP, et al. Ott WJ. The diagnosis of altered fetal growth. Obstet Gynecol Clin North Am. Duryea EL,et al. Obstet Gynecol. Odibo AO, et. Am J Perinatol. Epub Jul Committee opinion no method for estimating due date. Determination of Gestational Age by Ultrasound No. Hill LM, et. Salomon LJ, et. Reddy UM, etr. STT was measured from outer margin of skin to outer margin of femur shaft in the middle third of the thigh Figure 2. Actual birth weight BW also was measured immediately after birth.
Appropriate section of femoral bone achieved when probe is parallel to the femoral shaft. STT is defined as the distance between outer margins of skin to outer margin of femur shaft in the middle third of the thigh when magnified appropriate section is achieved.
Ultrasonic variables were used in millimeter mm unit as independent variables for synthesis of predicting formulas. Birth weight was measured in gram gr unit. Birth weight BW normality was tested by using Kolmogrov Smirnov test and due to lack of normality, log BW was considered as dependent variable. As an indicator of fitness of models for each combination of variables on birth weight R square was reported.
One hundred and fourteen cases participated in this study. Mean SD for maternal age was Descriptive statistics regarding to variables of the study is shown in table I. Predictive birth weight formulas derived by linear regression model are illustrated in table II. The highest R square 0. Predictive formulas in different combination of variables and their predictive power R square. Scattered diagram for the impression of A: abdominal circumference on birth weight R: 0. The results of present study provided new formulas for estimating fetal weight.
Recent studies which tried to take account to limb soft tissue parameters in predictive formulas are few. Different limb soft tissue variables which were used to improve fetal weight estimation models includes thigh volume obtained by cross sectional images, fractional thigh volume, fractional limb volume, mid-thigh tissue area, mid-thigh soft tissue thickness and fetal abdominal subcutaneous tissue and thigh muscle and fat 19 - Also those studies suggested new formulas by applying these variables 16 , 19 - Accuracy of some of these formulas was shown to be more than previous ones with less percentage of error 19 - Larciprete et al and Scioscia studies, like our study emphasize on the impression of mid-thigh soft tissue thickness on birth weight 24 , The former study noted the significant improvement of birth weight prediction models when mid-thigh tissue area is added to other standard ultrasound variables.
In previously published models attention was concentrated toward diameters of head, abdomen and femoral bone 26 - Among those variables, AC was shown to be of best predictive value 25 , 29 , The value of AC highly depends on its correct measurement by considering some strict rules including location of spine at 3 or 9 o'clock of the transverse section, observing stomach at left site, existence of only one rib and the junction of the umbilical segment of left and right portal vein in the section 10 , All these rules may not be achievable all time.
Intellectually, because fetal weight is directly correlated with fetal fat amount, it would be mostly correlated with limb soft tissue than AC as well. Studies that specifically were designed to determine the accuracy of this hypothesis are rare, however some comparisons were made during other studies. Santolaya-Forgas et al and Balouet et al studies introduced soft tissue parameters superior to AC in predicting birth weight 14 , It would be minded that these results may not be completely reliable for replacement of AC by STT but it can open a window for further researches.
It could be of much use when positioning of the fetus makes the correct measurement of AC be distorted. Besides, FL section itself and linear measurement of STT in this section is much easier than measurement of AC, especially for non-expert operators. In addition ethnicity may play role in fetal weight, there are limited Birth Weight formulas based on Iranian population 7.
Honarvar formula that has been shown to be accurate for Iranian population uses single measurement of femoral length 7 , 8. Since soft tissue parameters have not been used in this formula, it is not comparable with our result. Short interval between ultrasonography measurement and birth weight, obtaining measurements by expert radiologists, finding linear formulas, making new windows for further researches are benefits of our study.
J Clin Ultrasound. PMID: Ultrasonographic estimation of fetal weight: development of new model and assessment of performance of previous models. Antenatal magnetic resonance imaging versus ultrasound for predicting neonatal macrosomia: a systematic review and meta-analysis.
Br J Obstet Gynaecol. Antepartum detection of macrosomic fetus: clinical versus sonographic, including soft-tissue measurements. Obstet Gynecol. Arch Gynakol. Ultrasound versus clinical examination to estimate fetal weight at term. Geburtshilfe Frauenheilkd. Arch Gynecol Obstet. Influence of maternal body mass index on sonographic fetal weight estimation prior to scheduled delivery. J Obstet Gynaecol Res. Influence of maternal body mass index on the clinical estimation of fetal weight in term pregnancies.
Practice bulletin no. The effect of maternal obesity on the accuracy of fetal weight estimation. The effect of body mass index on three methods of fetal weight estimation. Analysis of factors influencing the ultrasonic fetal weight estimation. Fetal Diagn Ther. Prediction of small-for-gestational-age neonate by third-trimester fetal biometry and impact of ultrasound-delivery interval. Fetal Medicine Foundation fetal and neonatal population weight charts. The World Health Organization fetal growth charts: a multinational longitudinal study of ultrasound biometric measurements and estimated fetal weight.
PLoS Med. Effect of maternal weight on accuracy of maternal and physician estimate of fetal weight. J Reprod Med. PubMed Google Scholar. Ultrasonographic estimation of fetal weight in the clinically macrosomic fetus. Accuracy and modifying factors for ultrasonographic determination of fetal weight at term. Clinical and sonographic fetal weight estimates in active labor with ruptured membranes.
Validity of ultrasound estimation of fetal weight. Clinical accuracy of estimated fetal weight in term pregnancies in a teaching hospital.
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Comparison of clinical versus ultrasound estimation of fetal weight. Am J Perinatol. Clinical vs. A randomized clinical trial. A comparison of clinical and ultrasound estimation of fetal weight.
J Med Assoc Thail. CAS Google Scholar. Accuracy of ultrasound, clinical and maternal estimates of birth weight in term women. East Mediterr Health J. Clinical and patient estimation of fetal weight vs. Clinical and sonographic estimation of fetal weight performed during labor by residents.
Assessment of the accuracy of multiple sonographic fetal weight estimation formulas: a year experience from a single center.
J Ultrasound Med. Multivariable evaluation of term birth weight: a comparison between ultrasound biometry and symphysis-fundal height. Specific formulas improve the estimation of fetal weight by ultrasound scan.
Thilaganathan B.
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