Validity of ultrasound estimation of fetal weight

doi:10.1016/S0029-7844(00)00828-0

Obstetrics & Gynecology

Volume 95, Issue 6, Part 1, June 2000, Pages 856-860

https://doi.org/10.1016/S0029-7844(00)00828-0 Get rights and content

Abstract

Objective: To assess the validity of ultrasound estimation of fetal weight at term.

Methods: We conducted a prospective observational study whereby all ultrasonic biometric measurements were done by a single observer. Fifty pregnant women at term had ultrasonic measurement of various fetal biometric parameters performed within a week of delivery. Fetal weight was estimated by the use of four reported methods (Aoki, Campbell, Shepard, and Hadlock formulas). We compared estimated weight with the birth weight after the estimated fetal weight was adjusted by adding 25 g for each day between the ultrasound measurements and delivery.

Results: The adjusted estimated fetal weight obtained from all four formulas tended to be lower than measured birth weight. The smallest mean difference was obtained with the Shepard and Aoki formulas (51.4 g and 60.5 g, respectively), whereas the Campbell and Hadlock formulas produced larger mean differences (141.8 g and 190.7 g, respectively). The Aoki formula generated the smallest range between the limits of agreement (−324.2 to 445.2 g) whereas the Campbell formula produced the largest range (−286.5 to 570.1 g). The range between the limits of agreement generated with the Shepard and Hadlock formulas were intermediate between those produced by the Aoki and Campbell formulas. The intraclass correlation coefficients generated with the Aoki and Shepard formulas were identical (0.90). The intraclass correlation coefficients obtained with the Hadlock (0.84) and Campbell formulas (0.85) were lower.

Conclusion: The validity of ultrasonic estimation of fetal weight at term with all four formulas was high.

Section snippets

Materials and methods

We used purposive sampling from a larger study of 274 low-risk pregnant women participating in a study of serial ultrasound biometry.8 The criterion for selection was the measurement of four variables by ultrasound, biparietal diameter (BPD), femur length (FL), fetal abdominal area, and abdominal circumference (AC), within 7 days of delivery at term (over 37 weeks’) gestation. There were 50 (18%) subjects who satisfied that criterion. Gestational ages were calculated with reference to the

Results

The descriptive statistics of the ultrasonic biometric variables, adjusted ultrasonic fetal weight estimations using the four formulas, time, and the actual birth weights are shown in Table 2. The average time interval between ultrasonic assessment and delivery ± SD was 3.6 ± 1.9 days. The mean gestational age at delivery ± SD was 275.0 ± 6.5 days.

Figure 1 shows the agreement between the adjusted, ultrasound-estimated fetal weight and the actual birth weight assessed visually by the limits of

Discussion

Our study showed that fetal weight estimated by ultrasound using the Aoki, Campbell, Shepard, and Hadlock formulas is a valid estimate of actual weight. The credibility of our findings depends on the rigor of design, conduct, and analysis of our study. Our study fulfills the design and conduct criteria for bias in the assessment of validity in clinical measurements.16, 18, 21 In particular, we used an appropriate reference standard for fetal weight measurement, and the author who calculated the

References (22)

C.C. Lin et al.
Acid-base characteristics of fetuses with intrauterine growth retardation during labor and delivery
Am J Obstet Gynecol
(1980)
F.P. Hadlock et al.
Estimation of fetal weight with the use of head, body and femur measurements—A prospective study
Am J Obstet Gynecol
(1985)
G.I. Hirata et al.
Ultrasonographic estimation of fetal weight in the clinically macrosomic fetus
Am J Obstet Gynecol
(1990)
M.J. Shepard et al.
An evaluation of two equations for predicting fetal weight by ultrasound
Am J Obstet Gynecol
(1982)
N.V. Simon et al.
Influence of fetal growth patterns on sonographic estimation of fetal weight
J Clin Ultrasound
(1987)
R.L. Deter et al.
The use of ultrasound in the assessment of normal fetal growthA review
J Clin Ultrasound
(1981)
H.V.F. Jordaan
Estimation of fetal weight by ultrasound
J Clin Ultrasound
(1983)
L.M. Hill et al.
Evaluation of three methods for estimating fetal weight
J Clin Ultrasound
(1986)
P. Owen et al.
Standards for ultrasound fetal growth velocity
Br J Obstet Gynaecol
(1996)
R.T. Geirsson et al.
Certain dates may not provide a reliable estimate of gestational age
Br J Obstet Gynaecol
(1991)

S. Campbell

An improved method of fetal cephalometry by ultrasound

J Obstet Gynaecol Br Commonw

(1968)

Cited by (89)

Accuracy of estimated fetal weight assessment in fetuses with abdominal wall defects
2021, American Journal of Obstetrics and Gynecology MFM
Gastroschisis and omphalocele are congenital abdominal wall defects in which the bowel and other abdominal contents extrude from the fetal abdominal cavity. Standard formulas for estimated fetal weight using ultrasound include fetal abdominal circumference measurement and have a range of error of approximately 10%. It is unknown whether the accuracy of estimated fetal weight assessment is compromised in fetuses with abdominal wall defects because of the extrusion of abdominal contents.
This study aimed to assess the accuracy of standard estimated fetal weight assessment in fetuses with abdominal wall defects by comparing prenatal assessment of fetal weight with actual birthweight.
A retrospective cohort study of fetuses diagnosed with gastroschisis or omphalocele was performed at a single center from 2012 to 2018. Fetuses with additional anomalies or confirmed chromosome abnormalities were excluded. Estimated fetal weight was calculated using the Hadlock formula. Published estimates of fetal growth rate were used to establish a projected estimated fetal weight at birth from the final growth ultrasound, and the percent difference between projected estimated fetal weight at birth and actual birthweight was calculated. The Wilcoxon rank-sum test was used to examine the difference between projected estimated fetal weight and actual birthweight.
We had complete data for 112 fetuses with abdominal wall defects, including 85 with gastroschisis and 27 with omphalocele. The median (interquartile range) projected estimated fetal weight was similar to median birthweight, at 2283 g (interquartile range, 2000–2810) and 2306 g (interquartile range, 1991–264), respectively, which did not represent a statistically significant difference between projected estimated fetal weight and actual birthweight (P=.32). The median percent error was 6.8 (3.1–12.8). In addition, we did not find any statistical difference between projected estimated fetal weight and actual birthweight in patients with gastroschisis (P=.52) or omphalocele (P=.35) individually. Estimated fetal weight was underestimated in most cases (n=68 [60.7%]).
In fetuses with abdominal wall defects, standard measurement of fetal weight shows an accuracy that is at least comparable with previously established margins of error for ultrasound assessment of fetal weight. Standard estimated fetal weight assessment remains an appropriate method of estimating fetal weight in these fetuses.
Accuracy of estimated fetal weight assessment in fetuses with congenital diaphragmatic hernia
2020, American Journal of Obstetrics and Gynecology MFM
Congenital diaphragmatic hernia is a congenital anomaly in which fetal abdominal organs herniate into the thoracic cavity through a diaphragmatic defect, which can impede fetal lung development. Standard formulas for estimated fetal weight include measurement of fetal abdominal circumference, which may be inaccurate in fetuses with congenital diaphragmatic hernia because of displacement of abdominal contents into the thorax.
This study aimed to assess the accuracy of standard estimated fetal weight assessment in fetuses with congenital diaphragmatic hernia by comparing prenatal assessment of fetal weight with actual birthweight.
A retrospective cohort study of fetuses diagnosed with congenital diaphragmatic hernia was performed at a single center from 2012 to 2018. Fetuses with multiple anomalies or confirmed chromosome abnormalities were excluded. Estimated fetal weight was calculated using the Hadlock formula. Published estimates of fetal growth rate were used to establish a projected estimated fetal weight at birth from the final growth ultrasound, and the percentage difference between projected estimated fetal weight at birth and actual birthweight was calculated. A Wilcoxan rank-sum test was used to examine the difference between projected estimated fetal weight and birthweight.
We had complete data for 77 fetuses with congenital diaphragmatic hernia. The majority (76.6%, 55 of 77) had left-sided congenital diaphragmatic hernia. The median [interquartile range] projected estimated fetal weight was similar to median birthweight, at 3177 g [2691–3568] and 3180 g [2630–3500], respectively, which did not represent a statistically significant difference between projected estimated fetal weight and birthweight (P = .66). The median absolute percentage difference between projected birthweight and actual birthweight was 6.3% [3.2–7.0]. Estimated fetal weight was overall underestimated in a minority of cases (44.2%, 34 of 77).
In fetuses with a congenital diaphragmatic hernia, standard measurements of fetal estimated fetal weight show accuracy that is at least comparable with previously established margins of error for ultrasound assessment of fetal weight. Standard estimated fetal weight assessment remains an appropriate method of estimating fetal weight in fetuses with congenital diaphragmatic hernia.
Comparison of the Hadlock and INTERGROWTH formulas for calculating estimated fetal weight in a preterm population in France
2018, American Journal of Obstetrics and Gynecology
Accurate estimation of fetal weight is needed for growth monitoring and decision-making in obstetrics; the INTERGROWTH project developed an estimated fetal weight formula to construct new intrauterine growth standards.
We sought to compare the accuracy of the Hadlock and INTERGROWTH formulas for the estimation of fetal weight among preterm infants.
Using the EPIPAGE 2 population-based study of births between 22–34 weeks of gestation, we included 578 nonanomalous singleton fetuses with an ultrasound-to-delivery interval <2 days. We used abdominal circumference, head circumference, and femur length to calculate estimated fetal weight with Hadlock formula and abdominal and head circumferences to calculate estimated fetal weight according to INTERGROWTH. The mean percentage errors and the proportions of estimated fetal weight measures within ±10% of birthweight were compared between the 2 methods.
Mean (SD) gestational age and birthweight were 29.1 (SD 2.7) weeks and 1219 (SD 489) g. Mean (SD) percentage errors for Hadlock and INTERGROWTH were significantly different: –0.7 (SD 10.1) and –3.5 (SD 11.6), respectively (P < .001), and more infants were classified within ±10% of their birthweight with Hadlock compared to INTERGROWTH (68.7% vs 57.8%, P < .001). The INTERGROWTH formula overestimated birthweight at 22–23 weeks compared to Hadlock [mean errors of 18.8 (SD 13.6) vs 5.5 (SD 10.2)] and underestimated birthweight >28 weeks: at 29–31 weeks, mean errors were –5.8 (SD 10.9) for INTERGROWTH and –0.6 (SD 10.4) for Hadlock.
Hadlock estimated fetal weight formula was more accurate than INTERGROWTH formula for fetuses delivered between 22–34 weeks of gestation. Our results support continued use of Hadlock formula in France and raise questions about the applicability of INTERGROWTH intrauterine growth standards.
Patal Bisphenol-A exposure affects fetal length growth by maternal glutathione transferase polymorphisms, and neonatal exposure affects child volume growth by sex: From multiregional prospective birth cohort MOCEH study
2018, Science of the Total Environment
Citation Excerpt :
Gestational age was estimated based on the onset of the last menstrual period: if the last menstrual period was unreliable, or if there was a significant discordance between the ultrasonography and last menstrual period dating (> 10 days), the first ultrasonography estimation of the gestational age was used. The femur length was measured during the third trimester with ultrasound and estimated fetal weight was calculated by ultrasonic fetal weight estimation formulas (Chien et al., 2000). Trained nurses in the delivery room routinely measured birth weight using a digital scale at birth and recorded it on the patient's medical charts.
We aimed to evaluate the effects of Bisphenol-A (BPA) exposure on fetal/child growth from the fetal period to 72 months after birth. The MOCEH study is a prospective birth cohort study in Korea. A total of 788 mother-child pairs in the third trimester and 366 pairs in the neonatal period who completed BPA assessment and fetal/children growth outcomes were included. BPA assessments were conducted twice in the third trimester using maternal urines and the neonatal period using neonatal urines. Fetal femur length was measured with ultrasound, and estimated-fetal-weight was calculated. Child growth outcomes including three z-scores for age-specific length, weight-for-length (WFL) and weight were calculated. Analysis was performed according to infant sex and maternal glutathione transferases (GSTs) polymorphisms. When maternal urinary BPA concentration in the third trimester increased by 1 log-transformed unit of BPA/Cr, the third trimester femur length decreased 0.03(0.01) cm in the whole and 0.06(0.02) cm in the GSTM1/GSTT1 either null group. Then, maternal urinary BPA levels and birth outcomes were positively correlated. When the prenatal BPA concentration is increased by 1 log-transformed unit of BPA/Cr, the z-score for weight at birth increased 0.05(0.02) in whole and 0.06(0.03) in boys and the z-score for WFL at birth increased 0.05(0.02) in whole and 0.07(0.03) in girls. In linear mixed models, significant positive effects of the neonatal urinary BPA were found on WFL over the 72 months period. When the neonatal BPA concentration is increased by 1 log-transformed unit of BPA concentration, the z-score for weight through 6–72 months increased 0.09(0.03) in whole and 0.12(0.05) in girls. Our study suggests BPA exposure is negatively associated with intrauterine linear growth, but has a positive association with volume growth during childhood. Furthermore, intrauterine growth was affected by maternal GSTs polymorphism, and child growth was affected by sex.
The Accuracy of Estimating Fetal Weight and Inter-Twin Weight Discordance by Ultrasound in Twin Pregnancies in Women With Increased Body Mass Index
2015, Journal of Obstetrics and Gynaecology Canada
The purpose of this study was to determine whether increased maternal pre-pregnancy BMI in women with a twin pregnancy decreases the accuracy of fetal weight estimation by ultrasound and the estimation of inter-twin weight discordance when compared with women with a normal BMI and a twin pregnancy.
We conducted a retrospective cohort study of women with a known pre-pregnancy or early pregnancy BMI who delivered a viable twin pregnancy after 28 weeks’ gestation between 2008 and 2011, and who had an ultrasound examination for fetal weight estimation within two weeks of delivery. The sonographically estimated fetal weight (EFW) was compared with the actual weight for each twin, and inter-twin weight discordance (defined as a weight difference between twins of more than 25%) was stratified for the patient’s BMI. We sought to determine if EFW and inter-twin weight discordance were affected if delivery occurred at eight to 14 days after ultrasound compared to within seven days of ultrasound.
A total of 300 twin pregnancies with known pre-pregnancy maternal BMI were identified. Of these, 179 were underweight or of normal weight (BMI < 25 kg/m²), 67 were overweight (BMI 25 to 29.9 kg/m²), and 54 were obese (BMI ≥ 30 kg/m²). Ultrasound accuracy among all BMI groups were compared when done between 8 and 14 days and within seven days from delivery. There was a significant increasing trend in mean absolute percent errors for both twins in the obese compared to normal weight (P < 0.05) if delivery happened between eight and 14 days from ultrasound. This difference was diminished if the ultrasound was performed within seven days of delivery. The ultrasound detection of inter-twin weight discordance was similar among the three BMI groups.
Estimation of fetal weight using ultrasound in obese women with twin pregnancies appears to be more reliable when performed close to delivery.
Cette étude avait pour objectif de déterminer si la présence d'un IMC maternel prégrossesse accru entraînait une baisse de la précision de l'échographie pour ce qui est de l'estimation du poids fœtal et de la discordance intergémellaire en matière de poids dans le cadre de grossesses gémellaires, par comparaison avec des femmes présentant un IMC normal.
Nous avons mené une étude de cohorte rétrospective portant sur des femmes qui présentaient un IMC prégrossesse (ou aux débuts de la grossesse) connu, qui ont accouché après 28 semaines de gestation à la suite d'une grossesse gémellaire viable entre 2008 et 2011, et qui ont subi un examen échographique visant l'estimation du poids fœtal dans les deux semaines ayant précédé l'accouchement. Le poids fœtal estimé (PFE) par échographie a été comparé au poids réel de chacun des jumeaux, puis la discordance intergémellaire en matière de poids (définie comme une différence de poids entre les jumeaux de plus de 25 %) a été stratifiée en fonction de l'IMC de la patiente. Nous avons cherché à déterminer si le PFE et la discordance intergémellaire en matière de poids avaient été affectés lorsque l'accouchement était survenu de 8 à 14 jours à la suite de l'échographie, par comparaison avec un accouchement étant survenu dans les sept jours de la tenue de l'échographie.
Nous avons pu identifier, au total, 300 grossesses gémellaires pour lesquelles l'IMC maternel prégrossesse était connu : 179 femmes présentaient une insuffisance pondérale ou un poids normal (IMC < 25 kg/m²), 67 présentaient une surcharge pondérale (IMC = de 25 à 29,9 kg/m²) et 54 étaient obèses (IMC > 30 kg/m²). Dans tous les groupes d'IMC, la précision de l'échographie menée entre 8 et 14 jours avant l'accouchement a été comparée à celle de l'échographie menée dans les sept jours de l'accouchement. Une tendance à la hausse considérable en matière d'erreur absolue moyenne en pourcentage pour les deux jumeaux a été constatée chez les femmes obèses, par comparaison avec les femmes de poids normal (P < 0,05), lorsque l'accouchement avait eu lieu de 8 à 14 jours à la suite de l'échographie. Cette différence était moindre lorsque l'échographie avait été menée dans les sept jours de l'accouchement. La détection par échographie d'une discordance intergémellaire en matière de poids était semblable dans les trois groupes d'IMC.
Chez les femmes obèses qui connaissent une grossesse gémellaire, l'estimation du poids fœtal par échographie semble être plus fiable lorsqu'elle est menée peu avant l'accouchement
Which intrauterine growth restricted fetuses at term benefit from early labour induction? A secondary analysis of the DIGITAT randomised trial
2014, European Journal of Obstetrics and Gynecology and Reproductive Biology
The Disproportionate Intrauterine Growth Intervention Trial at Term (DIGITAT trial) showed that in women with suspected intrauterine growth restriction (IUGR) at term, there were no substantial outcome differences between induction of labour and expectant monitoring. The objective of the present analysis is to evaluate whether maternal or fetal markers could identify IUGR fetuses who would benefit from early labour induction.
The DIGITAT trial was a multicenter, parallel and open-label randomised controlled trial in women who had a singleton pregnancy beyond 36 + 0 weeks’ gestation with suspected IUGR (n = 650). Women had been randomly allocated to either labour induction or expectant monitoring. The primary outcome was a composite measure of adverse neonatal outcome, defined as neonatal death before hospital discharge, Apgar score <7, umbilical artery pH <7.05, or admission to neonatal intensive care. Using logistic regression modelling, we investigated associations between outcome and 17 markers, maternal characteristics and fetal sonographic and Doppler velocimetry measurements, all collected at study entry.
17 (5.3%) infants in the induction group had an adverse neonatal outcome compared to 20 (6.1%) in the expectant monitoring group. The only potentially informative marker for inducing labour was maternal pre-pregnancy body mass index (BMI). Otherwise, we observed at best weak associations between a benefit from labour induction and maternal age, ethnicity, smoking, parity, pregnancy-induced hypertension or preeclampsia, Bishop score and gestational age, or fetal sonographic markers (gender, estimated fetal weight, body measurements, oligohydramnios, or umbilical artery pulsatility index and end diastolic flow).
In late preterm and term pregnancies complicated by suspected intrauterine growth restriction, most of the known prognostic markers seem unlikely to be helpful in identifying women who could benefit from labour induction, except for maternal pre-pregnancy BMI.

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Validity of ultrasound estimation of fetal weight

Abstract

Section snippets

Materials and methods

Results

Discussion

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Influence of fetal growth patterns on sonographic estimation of fetal weight

J Clin Ultrasound

The use of ultrasound in the assessment of normal fetal growthA review

J Clin Ultrasound

Estimation of fetal weight by ultrasound

J Clin Ultrasound

Evaluation of three methods for estimating fetal weight

J Clin Ultrasound

Standards for ultrasound fetal growth velocity

Br J Obstet Gynaecol

Certain dates may not provide a reliable estimate of gestational age

Br J Obstet Gynaecol

An improved method of fetal cephalometry by ultrasound

J Obstet Gynaecol Br Commonw