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Three fetal growth standards disagree on which fetuses are small

Three major sets of fetal growth charts, one from the United States and two international, give different weights for a typical baby at 39 weeks and so flag different babies as small. There is no agreed single chart, and the effect of the choice on illness and death has not been compared.

  • Bottleneck
  • In this atlas

Overview

Technical summary

The 2018 expert review (PMID 29275821) compares the NICHD, INTERGROWTH-21st and a WHO study and reports different 50th percentile estimated fetal weights at 39 weeks, and says different percentages of small- and large-for-gestational-age fetuses will be identified. It lists the comparison of misclassification against morbidity and mortality as an important data gap and notes that cut points may need to be tighter (2.5th or 97.5th) or set in local populations. The SMFM definition of growth restriction uses a 10th percentile line set by a chart, so the choice matters for diagnosis.

Scope

Fetuses of women with low-risk pregnancies as described by three growth cohorts; the effect on babies of using one chart or another is not compared in the sources read

Stage
Interpreting a growth scan: choosing the reference chart that sets the small-baby line
Why it is severe
The review says different charts identify different percentages of small and large fetuses, and that comparing misclassification against illness and death under different criteria is an important data gap.

Burden

  • Description Evidence synthesis Certainty not assessed

    An expert review compared three recently completed longitudinal cohort studies that built fetal growth charts: the NICHD Fetal Growth Studies in the United States and two international studies (INTERGROWTH-21st and a World Health Organization study). All three included low-risk women, yet the percentiles for fetal measures and estimated fetal weight varied between them. At 39 weeks the 50th percentile estimated fetal weight was 3502 g for white, 3330 g for Hispanic, 3263 g for Asian and 3256 g for Black women in the NICHD study, compared with 3186 g for INTERGROWTH and 3403 g for the WHO study. The review says that applying these standards to a clinical population will identify different percentages of small- and large-for-gestational-age fetuses, and that comparing misclassification of small and large fetuses in relation to illness and death under different criteria is an important data gap.

    Applies to Fetal
    • Fetuses of women with low-risk pregnancies in three recently completed longitudinal cohort studies that developed fetal growth charts, one in the United States and two international. The review compares the aims, sampling frames and analytic approaches.
    • Not stated in the review abstract
    • United States (NICHD study) and international (INTERGROWTH-21st and the WHO study)
    • Pregnancy
    • Gestational age Not reported
    • Postnatal age Not reported
    Follow-up Not stated in the parts of the source that were read.
    Certainty method
    Not assessed
    Limitations
    This is a narrative expert review by authors connected to the NICHD study (PubMed lists NIH intramural support), not a systematic review. The review names its third study the World Health Organization Multicentre Growth Reference Study; the abstract does not say whether that is the same publication as the WHO fetal growth charts paper in this atlas, so the two are not linked here. Only the abstract was read, and the figures are the review's own.
    Last checked
    2026-10-14
    Next evidence check due
    Not scheduled
    Sources and citations (11)

    1. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 1
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    2. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 2, fragment 1 of 2
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    3. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 2, fragment 2 of 2
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    4. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 11
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    5. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 12, fragment 1 of 3
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    6. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 12, fragment 2 of 3
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    7. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 12, fragment 3 of 3
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    8. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 13, fragment 1 of 2
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    9. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 13, fragment 2 of 2
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    10. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 15, fragment 1 of 2
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    11. Supports Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

      Publication · American journal of obstetrics and gynecology · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities, retrieved 2026-10-14. The full text and the version of record were not read. · Published 2017-12-22 · DOI: 10.1016/j.ajog.2017.11.593 · PMID: 29275821

      Locator
      Abstract, sentence 15, fragment 2 of 2
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      fd5963be0dc6a68d10e4c9182534ffbe44918aff9de7eb9f4500341a687c9078
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

Current efforts

None stated in this record.

Record details

Record id
maternal:bottleneck-fetal-growth-standard-choice
Content hash
ce1745f592ff70d072983e31c249b356813483e6c7e576fcde981bc12dd875be