A Test of Agreement of Customised Birthweight Models

Gibbons, Kristen; Chang, Allan; Flenady, Vicki; Mahomed, Kassam; Gray, Peter H.; Gardener, Glenn; Rossouw, Dominique

doi:10.1111/ppe.12041

Cited by 6 publications

(5 citation statements)

References 30 publications

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Section: Discussionsupporting

confidence: 83%

“…The coefficients on maternal and fetal characteristics obtained in the birthweight models were similar for both samples and consistent with Gardosi’s model, 11 French customized charts 15 and studies from other countries. 15 , 41 One exception was the low coefficient for high parity (≥4) in ELFE, but few women were in this category. In contrast, we found an inconsistent association of fetal and maternal characteristics with EFW, with magnitudes generally less pronounced than at birth, as has been reported elsewhere for maternal height and body mass index.…”

Section: Discussionmentioning

confidence: 99%

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Testing the assumptions of customized intrauterine growth charts using national birth studies

Hocquette

Monier

Blondel

et al. 2022

Acta Obstet Gynecol Scand

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Introduction Customized intrauterine growth charts are widely used for growth monitoring and research. They are based on three assumptions: (1) estimated fetal weight (EFW) has a normal distribution with a constant coefficient of variation at all gestational ages; (2) Hadlock’s growth curve accurately describes the relation between EFW and gestational ages; (3) associations between EFW and the fetal and maternal characteristics included in the customization model (fetal sex, pre‐pregnancy weight, height, parity) are proportional throughout pregnancy. The aim of this study was to test whether these underlying assumptions are verified. Material and methods Data came from (1) the French Longitudinal Study of Children (ELFE) cohort, which recruited births after 32 weeks' gestation in 349 maternity hospitals in France in 2011, and (2) the National Perinatal Survey, which included births from all French maternity hospitals in 2016. The study population included, respectively, 6 920 and 8 969 singleton non‐malformed term live births with data on customization characteristics and EFW. We computed the coefficient of variation by gestational age and then modeled the association of gestational age, maternal and fetal characteristics with EFW at the second and third trimester ultrasound and with birthweight using linear regression. To assess the proportionality of the impact of maternal and fetal characteristics, we computed the percent change in weight associated with these characteristics at these three time points. Results The coefficient of variation was close to 12% at each gestational age, but EFW was not normally distributed, leading to small but systematic underestimation of fetuses under the 10th percentile. Weights representing the 50th and 10th percentiles based on Hadlock’s growth trajectory were lower than observed or predicted weights. Most characteristics more strongly impacted weight at birth than during pregnancy. In the French Longitudinal study of Children (ELFE) cohort, boys were 1.8% (95% confidence interval [CI] 1.3–2.4) heavier than girls in the third trimester, whereas this percentage was 4.6% (95% CI 4.0–5.2) at birth. In the National Perinatal Survey, these percentages were 2.3% (95% CI 1.8–2.8) and 4.3% (95% CI 3.8–4.8). Conclusions These results from two independent sources revealed discrepancies between routine clinical EFW data used for growth monitoring and the customized growth model’s assumptions.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Testing the assumptions of customized intrauterine growth charts using national birth studies

Hocquette

Monier

Blondel

et al. 2022

Acta Obstet Gynecol Scand

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show abstract

“…The second limitation was that our references relied on the untested assumption that Hadlock's formula could be transposed to any population and that the coefficient of variation remains constant across all gestational ages. Nevertheless, the Hadlock's growth references and Gardosi's customised model are widely used in multiple countries for clinical care and research and many intra‐uterine growth models assume that the coefficient of variation is constant . We were able to compare our model with Swedish national intra‐uterine references for the Swedish infants in our sample and observed high concordance for SGA prevalence, despite slight differences in percentile values, which have been noted in other comparisons .…”

Section: Discussionmentioning

confidence: 56%

Variation in term birthweight across European countries affects the prevalence of small for gestational age among very preterm infants

et al. 2017

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“…The association of fetal growth with other pregnancy outcomes, such as neonatal mortality and morbidity, was not investigated in this study. There is substantial uncertainty about the performance of different norms adjusting for fetal growth determinants [40],[41]. This study was not designed to compare customized norms.…”

Section: Discussionmentioning

confidence: 99%