Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes: are current charts adequate? An observational study from the Born in Bradford cohort

T Norris; W Johnson; D Farrar; D Tuffnell; J Wright; N Cameron

doi:10.1136/bmjopen-2014-006743

Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes: are current charts adequate? An observational study from the Born in Bradford cohort

T Norris, W Johnson, D Farrar, D Tuffnell, J Wright, N Cameron

Bristol Medical School (PHS)

Research output: Contribution to journal › Article (Academic Journal) › peer-review

32 Citations (Scopus)

Abstract

OBJECTIVES: Construct an ethnic-specific chart and compare the prediction of adverse outcomes using this chart with the clinically recommended UK-WHO and customised birth weight charts using cut-offs for small-for-gestational age (SGA: birth weight <10th centile) and large-for-gestational age (LGA: birth weight >90th centile).

DESIGN: Prospective cohort study.

SETTING: Born in Bradford (BiB) study, UK.

PARTICIPANTS: 3980 White British and 4448 Pakistani infants with complete data for gestational age, birth weight, ethnicity, maternal height, weight and parity.

MAIN OUTCOME MEASURES: Prevalence of SGA and LGA, using the three charts and indicators of diagnostic utility (sensitivity, specificity and area under the receiver operating characteristic (AUROC)) of these chart-specific cut-offs to predict delivery and neonatal outcomes and a composite outcome.

RESULTS: In White British and Pakistani infants, the prevalence of SGA and LGA differed depending on the chart used. Increased risk of SGA was observed when using the UK-WHO and customised charts as opposed to the ethnic-specific chart, while the opposite was apparent when classifying LGA infants. However, the predictive utility of all three charts to identify adverse clinical outcomes was poor, with only the prediction of shoulder dystocia achieving an AUROC>0.62 on all three charts.

CONCLUSIONS: Despite being recommended in national clinical guidelines, the UK-WHO and customised birth weight charts perform poorly at identifying infants at risk of adverse neonatal outcomes. Being small or large may increase the risk of an adverse outcome; however, size alone is not sensitive or specific enough with current detection to be useful. However, a significant amount of missing data for some of the outcomes may have limited the power needed to determine true associations.

Original language	English
Pages (from-to)	e006743
Journal	BMJ Open
Volume	5
Issue number	3
DOIs	https://doi.org/10.1136/bmjopen-2014-006743
Publication status	Published - 2015

Keywords

Adult
Area Under Curve
Birth Weight
Delivery, Obstetric
Dystocia
Female
Gestational Age
Great Britain
Humans
Infant, Newborn
Infant, Small for Gestational Age
Male
Medical Records
Obstetric Labor Complications
Pakistan
Pregnancy
Pregnancy Outcome
Prospective Studies
ROC Curve
Risk Factors
Young Adult

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Norris, T., Johnson, W., Farrar, D., Tuffnell, D., Wright, J., & Cameron, N. (2015). Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes: are current charts adequate? An observational study from the Born in Bradford cohort. BMJ Open, 5(3), e006743. https://doi.org/10.1136/bmjopen-2014-006743

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title = "Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes: are current charts adequate? An observational study from the Born in Bradford cohort",

abstract = "OBJECTIVES: Construct an ethnic-specific chart and compare the prediction of adverse outcomes using this chart with the clinically recommended UK-WHO and customised birth weight charts using cut-offs for small-for-gestational age (SGA: birth weight <10th centile) and large-for-gestational age (LGA: birth weight >90th centile).DESIGN: Prospective cohort study.SETTING: Born in Bradford (BiB) study, UK.PARTICIPANTS: 3980 White British and 4448 Pakistani infants with complete data for gestational age, birth weight, ethnicity, maternal height, weight and parity.MAIN OUTCOME MEASURES: Prevalence of SGA and LGA, using the three charts and indicators of diagnostic utility (sensitivity, specificity and area under the receiver operating characteristic (AUROC)) of these chart-specific cut-offs to predict delivery and neonatal outcomes and a composite outcome.RESULTS: In White British and Pakistani infants, the prevalence of SGA and LGA differed depending on the chart used. Increased risk of SGA was observed when using the UK-WHO and customised charts as opposed to the ethnic-specific chart, while the opposite was apparent when classifying LGA infants. However, the predictive utility of all three charts to identify adverse clinical outcomes was poor, with only the prediction of shoulder dystocia achieving an AUROC>0.62 on all three charts.CONCLUSIONS: Despite being recommended in national clinical guidelines, the UK-WHO and customised birth weight charts perform poorly at identifying infants at risk of adverse neonatal outcomes. Being small or large may increase the risk of an adverse outcome; however, size alone is not sensitive or specific enough with current detection to be useful. However, a significant amount of missing data for some of the outcomes may have limited the power needed to determine true associations.",

keywords = "Adult, Area Under Curve, Birth Weight, Delivery, Obstetric, Dystocia, Female, Gestational Age, Great Britain, Humans, Infant, Newborn, Infant, Small for Gestational Age, Male, Medical Records, Obstetric Labor Complications, Pakistan, Pregnancy, Pregnancy Outcome, Prospective Studies, ROC Curve, Risk Factors, Young Adult",

author = "T Norris and W Johnson and D Farrar and D Tuffnell and J Wright and N Cameron",

note = "Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.",

year = "2015",

doi = "10.1136/bmjopen-2014-006743",

language = "English",

volume = "5",

pages = "e006743",

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publisher = "BMJ Publishing Group",

number = "3",

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Norris, T, Johnson, W, Farrar, D, Tuffnell, D, Wright, J & Cameron, N 2015, 'Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes: are current charts adequate? An observational study from the Born in Bradford cohort', BMJ Open, vol. 5, no. 3, pp. e006743. https://doi.org/10.1136/bmjopen-2014-006743

Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes: are current charts adequate? An observational study from the Born in Bradford cohort. / Norris, T; Johnson, W; Farrar, D et al.
In: BMJ Open, Vol. 5, No. 3, 2015, p. e006743.

Research output: Contribution to journal › Article (Academic Journal) › peer-review

TY - JOUR

T1 - Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes

T2 - are current charts adequate? An observational study from the Born in Bradford cohort

AU - Norris, T

AU - Johnson, W

AU - Farrar, D

AU - Tuffnell, D

AU - Wright, J

AU - Cameron, N

N1 - Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

PY - 2015

Y1 - 2015

N2 - OBJECTIVES: Construct an ethnic-specific chart and compare the prediction of adverse outcomes using this chart with the clinically recommended UK-WHO and customised birth weight charts using cut-offs for small-for-gestational age (SGA: birth weight <10th centile) and large-for-gestational age (LGA: birth weight >90th centile).DESIGN: Prospective cohort study.SETTING: Born in Bradford (BiB) study, UK.PARTICIPANTS: 3980 White British and 4448 Pakistani infants with complete data for gestational age, birth weight, ethnicity, maternal height, weight and parity.MAIN OUTCOME MEASURES: Prevalence of SGA and LGA, using the three charts and indicators of diagnostic utility (sensitivity, specificity and area under the receiver operating characteristic (AUROC)) of these chart-specific cut-offs to predict delivery and neonatal outcomes and a composite outcome.RESULTS: In White British and Pakistani infants, the prevalence of SGA and LGA differed depending on the chart used. Increased risk of SGA was observed when using the UK-WHO and customised charts as opposed to the ethnic-specific chart, while the opposite was apparent when classifying LGA infants. However, the predictive utility of all three charts to identify adverse clinical outcomes was poor, with only the prediction of shoulder dystocia achieving an AUROC>0.62 on all three charts.CONCLUSIONS: Despite being recommended in national clinical guidelines, the UK-WHO and customised birth weight charts perform poorly at identifying infants at risk of adverse neonatal outcomes. Being small or large may increase the risk of an adverse outcome; however, size alone is not sensitive or specific enough with current detection to be useful. However, a significant amount of missing data for some of the outcomes may have limited the power needed to determine true associations.

AB - OBJECTIVES: Construct an ethnic-specific chart and compare the prediction of adverse outcomes using this chart with the clinically recommended UK-WHO and customised birth weight charts using cut-offs for small-for-gestational age (SGA: birth weight <10th centile) and large-for-gestational age (LGA: birth weight >90th centile).DESIGN: Prospective cohort study.SETTING: Born in Bradford (BiB) study, UK.PARTICIPANTS: 3980 White British and 4448 Pakistani infants with complete data for gestational age, birth weight, ethnicity, maternal height, weight and parity.MAIN OUTCOME MEASURES: Prevalence of SGA and LGA, using the three charts and indicators of diagnostic utility (sensitivity, specificity and area under the receiver operating characteristic (AUROC)) of these chart-specific cut-offs to predict delivery and neonatal outcomes and a composite outcome.RESULTS: In White British and Pakistani infants, the prevalence of SGA and LGA differed depending on the chart used. Increased risk of SGA was observed when using the UK-WHO and customised charts as opposed to the ethnic-specific chart, while the opposite was apparent when classifying LGA infants. However, the predictive utility of all three charts to identify adverse clinical outcomes was poor, with only the prediction of shoulder dystocia achieving an AUROC>0.62 on all three charts.CONCLUSIONS: Despite being recommended in national clinical guidelines, the UK-WHO and customised birth weight charts perform poorly at identifying infants at risk of adverse neonatal outcomes. Being small or large may increase the risk of an adverse outcome; however, size alone is not sensitive or specific enough with current detection to be useful. However, a significant amount of missing data for some of the outcomes may have limited the power needed to determine true associations.

KW - Adult

KW - Area Under Curve

KW - Birth Weight

KW - Delivery, Obstetric

KW - Dystocia

KW - Female

KW - Gestational Age

KW - Great Britain

KW - Humans

KW - Infant, Newborn

KW - Infant, Small for Gestational Age

KW - Male

KW - Medical Records

KW - Obstetric Labor Complications

KW - Pakistan

KW - Pregnancy

KW - Pregnancy Outcome

KW - Prospective Studies

KW - ROC Curve

KW - Risk Factors

KW - Young Adult

U2 - 10.1136/bmjopen-2014-006743

DO - 10.1136/bmjopen-2014-006743

M3 - Article (Academic Journal)

C2 - 25783424

SN - 2044-6055

VL - 5

SP - e006743

JO - BMJ Open

JF - BMJ Open

IS - 3

ER -