Reduction of false-positive diagnosis of fetal growth restriction by application of customized fetal growth standards

doi:10.1016/0029-7844(96)00285-2

Obstetrics & Gynecology

Volume 88, Issue 5, November 1996, Pages 844-848

https://doi.org/10.1016/0029-7844(96)00285-2 Get rights and content

Objective

To evaluate the clinical performance of fetal growth charts adjusted for individual maternal characteristics.

Methods

The study group consisted of 267 low-risk singleton pregnancies with normal clinical outcome. Mothers were recruited prospectively after the booking visit, then underwent three to five ultrasound examinations for fetal weight estimation. Individual growth curves were generated from these data and the birth weight, based on logpolynomial growth model. Computer software was written to calculate the number of fetal growth curves that cross the tenth percentile limit, based on an unadjusted, average ultrasound standard for our population, compared with the number that cross this limit if it is customized for known pregnancy characteristics such as maternal height, booking weight, parity, and ethnic group.

Results

Individual growth trajectories of this group of pregnancies with normal outcome were significantly less likely to cross below the tenth percentile for fetal weight when using customized growth charts than when the un-adjusted standard was used (McNemar's test, P < .001).

Conclusion

The relationship between maternal characteristics and fetal size needs to be considered in the assessment of fetal growth. The use of a customized standard reduces the false-positive rate for the diagnosis of growth restriction in a normal population.

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Cited by (123)

Stillbirth risk and smallness for gestational age according to Hadlock, INTERGROWTH-21st, WHO, and GROW fetal weight standards: analysis by maternal ethnicity and body mass index
2023, American Journal of Obstetrics and Gynecology
Appropriate growth charts are essential for fetal surveillance, to confirm that growth is proceeding normally and to identify pregnancies that are at risk. Many stillbirths are avoidable through antenatal detection of the small-for-gestational-age fetus. In the absence of an international consensus on which growth chart to use, it is essential that clinical practice reflects outcome-based evidence.
This study investigated the performance of 4 internationally used fetal weight standards and their ability to identify stillbirth risk in different ethnic and maternal size groups of a heterogeneous population.
We analyzed routinely collected maternity data from more than 2.2 million pregnancies. Three population-based fetal weight standards (Hadlock, Intergrowth-21st, and World Health Organization) were compared with the customized GROW standard that was adjusted for maternal height, weight, parity, and ethnic origin. Small-for-gestational-age birthweight and stillbirth risk were determined for the 2 largest ethnic groups in our population (British European and South Asian), in 5 body mass index categories, and in 4 maternal size groups with normal body mass index (18.5–25.0 kg/m²). The differences in trend between stillbirth and small-for-gestational-age rates were assessed using the Clogg z test, and differences between stillbirths and body mass index groups were assessed using the chi-square trend test.
Stillbirth rates (per 1000) were higher in South Asian pregnancies (5.51) than British-European pregnancies (3.89) (P<.01) and increased in both groups with increasing body mass index (P<.01). Small-for-gestational-age rates were 2 to 3-fold higher for South Asian babies than British European babies according to the population-average standards (Hadlock: 26.2% vs 12.2%; Intergrowth-21st: 12.1% vs 4.9%; World Health Organization: 32.2% vs 16.0%) but were similar by the customized GROW standard (14.0% vs 13.6%). Despite the wide variation, each standard’s small-for-gestation-age cases had increased stillbirth risk compared with non–small-for-gestation-age cases, with the magnitude of risk inversely proportional to the rate of cases defined as small for gestational age. All standards had similar stillbirth risk when the small-for-gestation-age rate was fixed at 10% by varying their respective thresholds for defining small for gestational age. When analyzed across body mass index subgroups, the small-for-gestation-age rate according to the GROW standard increased with increasing stillbirth rate, whereas small-for-gestation-age rates according to Hadlock, Intergrowth-21st, and World Health Organization fetal weight standards declined with increasing body mass index, showing a difference in trend (P<.01) to stillbirth rates across body mass index groups. In the normal body mass index subgroup, stillbirth rates showed little variation across maternal size groups; this trend was followed by GROW–based small-for-gestation-age rates, whereas small-for-gestation-age rates defined by each population-average standard declined with increasing maternal size.
Comparisons between population-average and customized fetal growth charts require examination of how well each standard identifies pregnancies at risk of adverse outcomes within subgroups of any heterogeneous population. In both ethnic groups studied, increasing maternal body mass index was accompanied by increasing stillbirth risk, and this trend was reflected in more pregnancies being identified as small for gestational age only by the customized standard. In contrast, small-for-gestation-age rates fell according to each population-average standard, thereby hiding the increased stillbirth risk associated with high maternal body mass index.
Counterpoint
2019, American Journal of Obstetrics and Gynecology
Customized growth charts: rationale, validation and clinical benefits
2018, American Journal of Obstetrics and Gynecology
Citation Excerpt :
The clinical implication is that small mothers with normally small babies may be subjected to unnecessary investigations, interventions, and anxiety and that large mothers are reassured falsely when being assessed with the use of a one-size-fits-all chart that does not take individual variation into account. Customized charts reduce false-positive diagnoses of SGA when ultrasound estimated fetal weight measurements are plotted on customized vs uncustomized fetal weight curves.55 This becomes most apparent in our multiethnic population, a large proportion of which are of South Asian origin.
Appropriate standards for the assessment of fetal growth and birthweight are central to good clinical care, and have become even more important with increasing evidence that growth-related adverse outcomes are potentially avoidable. Standards need to be evidence based and validated against pregnancy outcome and able to demonstrate utility and effectiveness. A review of proposals by the Intergrowth consortium to adopt their single international standard finds little support for the claim that the cases that it identifies as small are due to malnutrition or stunting, and substantial evidence that there is normal physiologic variation between different countries and ethnic groups. It is possible that the one-size-fits-all standard ends up fitting no one and could be harmful if implemented. An alternative is the concept of country-specific charts that can improve the association between abnormal growth and adverse outcome. However, such standards ignore individual physiologic variation that affects fetal growth, which exists in any heterogeneous population and exceeds intercountry differences. It is therefore more logical to adjust for the characteristics of each mother, taking her ethnic origin and her height, weight, and parity into account, and to set a growth and birthweight standard for each pregnancy against which actual growth can be assessed. A customized standard better reflects adverse pregnancy outcome at both ends of the fetal size spectrum and has increased clinicians’ confidence in growth assessment, while providing reassurance when abnormal size merely represents physiologic variation. Rollout in the United Kingdom has proceeded as part of the comprehensive Growth Assessment Protocol (GAP), and has resulted in a steady increase in antenatal detection of babies who are at risk because of fetal growth restriction. This in turn has been accompanied by a year-on-year drop in stillbirth rates to their lowest ever levels in England. A global version of customized growth charts with over 100 ethnic origin categories is being launched in 2018, and will provide an individualized, yet universally applicable, standard for fetal growth.
Does customized weight curves improve prenatal diagnosis of fetuses small for gestational age in a high-risk population?
2017, Revue Sage - Femme
Évaluer les performances des courbes de poids personnalisées dans le dépistage échographique anténatal des fœtus petits pour l’âge gestationnel dans une population de prématurés à haut risque de morbidité néonatale.
Tous les enfants nés prématurés à la maternité universitaire de type 3 de Nancy pendant un an et classés petits pour l’âge gestationnel à la naissance selon les courbes personnalisées développées par Ego et al. ont été inclus dans cette étude rétrospective. Lors de l’échographie la plus proche du terme, la performance des courbes de croissance personnalisées a été comparée à celle des courbes de croissance en population pour le dépistage anténatal d’un groupe de prématurés classés petits pour l’âge gestationnel (PPAG) en postnatal par une courbe personnalisée (ce reclassement permettant d’identifier une sous-population de PPAG prématurés à haut risque de morbidité néonatale).
Au total 67 nouveau-nés ont été inclus. Cinquante et un (76,1 %) avaient été reclassés en postnatal PPAG sur des courbes personnalisées alors qu’ils étaient considérés eutrophes sur une courbe postnatale en population et 16 (23,9 %) étaient PPAG selon les 2 courbes. Le délai moyen entre la dernière échographie et la naissance était de 2,2 semaines (± 2,5). Au seuil du dixième percentile, la sensibilité d’une courbe personnalisée pour la détection anténatale des fœtus reclassés en postnatal PPAG à l’aide de courbes personnalisées n’était pas différente de celle d’une courbe en population (29,9 % versus 41,8 % p = 0,05).
Dans notre étude la performance des courbes personnalisées de poids n’était pas différente de celle des courbes en population pour le dépistage anténatal des nouveau-nés prématurés reclassés petits pour l’âge gestationnel en postnatal à l’aide de courbes personnalisées.
To assess the accuracy of customized growth charts for the ultrasound antenatal diagnostic of fetus small for gestational age in a high-risk population of preterm.
All premature infants born in a French university maternity center for a year and classified as small for gestational age at birth by using customized growth charts developed by Ego et al. were included in this retrospective study. At the ultrasound performed closest to the term, customized growth charts and population growth curves were compared for the antenatal diagnosis of a premature infants group classified small for gestational age in post-natal by customized growth charts and more at risk of perinatal complications.
Sixty-seven newborns were included in the study. Fifty-one (76.1%) were secondarily classified as small for gestational age although they were eutrophic on the basis of population growth curves and 16 (23.9%) were small for gestational age on both curves. The average time between the last ultrasound and birth was 2.2weeks. On the threshold of the tenth percentile, the sensitivities of customized growth charts and curves in population were not significantly different (29.85% versus 41.79% P = 0.05) for antenatal detection of fetus small for gestational age.
In our study, the use of customized growth charts does not improve the antenatal detection of most at-risk children.
Does customized weight curves improve prenatal diagnosis of fetuses small for gestational age in a high-risk population?
2017, Gynecologie Obstetrique Fertilite et Senologie
Évaluer les performances des courbes de poids personnalisées dans le dépistage échographique anténatal des fœtus petits pour l’âge gestationnel dans une population de prématurés à haut risque de morbidité néonatale.
Tous les enfants nés prématurés à la maternité universitaire de type 3 de Nancy pendant un an et classés petits pour l’âge gestationnel à la naissance selon les courbes personnalisées développées par Ego et al. ont été inclus dans cette étude rétrospective. Lors de l’échographie la plus proche du terme, la performance des courbes de croissance personnalisées a été comparée à celle des courbes de croissance en population pour le dépistage anténatal d’un groupe de prématurés classés petits pour l’âge gestationnel (PPAG) en postnatal par une courbe personnalisée (ce reclassement permettant d’identifier une sous-population de PPAG prématurés à haut risque de morbidité néonatale).
Au total 67 nouveau-nés ont été inclus. Cinquante et un (76,1 %) avaient été reclassés en postnatal PPAG sur des courbes personnalisées alors qu’ils étaient considérés eutrophes sur une courbe postnatale en population et 16 (23,9 %) étaient PPAG selon les 2 courbes. Le délai moyen entre la dernière échographie et la naissance était de 2,2 semaines (± 2,5). Au seuil du dixième percentile, la sensibilité d’une courbe personnalisée pour la détection anténatale des fœtus reclassés en postnatal PPAG à l’aide de courbes personnalisées n’était pas différente de celle d’une courbe en population (29,9 % versus 41,8 % p = 0,05).
Dans notre étude la performance des courbes personnalisées de poids n’était pas différente de celle des courbes en population pour le dépistage anténatal des nouveau-nés prématurés reclassés petits pour l’âge gestationnel en postnatal à l’aide de courbes personnalisées.
To assess the accuracy of customized growth charts for the ultrasound antenatal diagnostic of fetus small for gestational age in a high-risk population of preterm.
All premature infants born in a French university maternity center for a year and classified as small for gestational age at birth by using customized growth charts developed by Ego et al. were included in this retrospective study. At the ultrasound performed closest to the term, customized growth charts and population growth curves were compared for the antenatal diagnosis of a premature infants group classified small for gestational age in post-natal by customized growth charts and more at risk of perinatal complications.
Sixty-seven newborns were included in the study. Fifty-one (76.1%) were secondarily classified as small for gestational age although they were eutrophic on the basis of population growth curves and 16 (23.9%) were small for gestational age on both curves. The average time between the last ultrasound and birth was 2.2 weeks. On the threshold of the tenth percentile, the sensitivities of customized growth charts and curves in population were not significantly different (29.85% versus 41.79% P = 0.05) for antenatal detection of fetus small for gestational age.
In our study, the use of customized growth charts does not improve the antenatal detection of most at-risk children.
Toward safe standards for assessment of fetal growth in twin pregnancy
2017, American Journal of Obstetrics and Gynecology

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Reduction of false-positive diagnosis of fetal growth restriction by application of customized fetal growth standards

Objective

Methods

Results

Conclusion

Lancet

Am J Obstet Gynecol

Radiology

Ultrasound Obstet Gynecol

Z Geburtschilfe Perinatal

Am J Obstet Gynecol

Ultrasound Obstet Gynecol

An adjustable fetal weight standard

Ultrasound Obstet Gynecol

Longitudinal study of fetal growth in subgroups of a low-risk population

Ultrasound Obstet Gynecol