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The missing data problem in birth weight percentiles and thresholds for "small-for-gestational-age"

Jennifer A Hutcheon1, Robert W Platt

  • 1Department of Epidemiology and Biostatistics, McGill University Faculty of Medicine, Montreal, Quebec, Canada. jennifer.hutcheon@mail.mcgill.ca

American Journal of Epidemiology
|March 18, 2008
PubMed

Insights

Conventional weight-for-gestational-age charts for identifying small-for-gestational-age infants are biased due to missing fetal weight data. New methods are needed for unbiased assessment of fetal growth and restriction risks.

Area of Science:

  • Perinatal epidemiology
  • Fetal growth research

Background:

  • Weight-for-gestational-age charts traditionally define small-for-gestational-age infants using livebirth data.
  • These charts have significant limitations for preterm infants due to missing in-utero fetal weight data.

Purpose of the Study:

  • To address the bias in current small-for-gestational-age definitions.
  • To propose methods for unbiased perinatal weight percentile calculation.

Main Methods:

  • Critically evaluate existing weight-for-gestational-age chart methodologies.
  • Discuss the impact of missing fetal weight data on etiologic studies.
  • Recommend standard epidemiologic approaches for handling missing data.

Main Results:

  • Livebirth-based references introduce considerable bias in etiologic studies of fetal growth restriction.
  • Missing data on in-utero fetal weights are a major limitation, especially for preterm infants.

Conclusions:

  • Standard epidemiologic methods for missing data are crucial.
  • Unbiased perinatal weight percentiles are necessary for accurate fetal growth assessment.
  • Improved methods will enhance understanding of fetal growth restriction risks.

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