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Optimal birth weight percentile cut-offs in defining small- or large-for-gestational-age

H Xu1, F Simonet, Z-C Luo

  • 1Department of Obstetrics and Gynecology, Sainte-Justine Hospital, University of Montreal, Montreal, Canada.

Acta Paediatrica (Oslo, Norway : 1992)
|January 13, 2010
PubMed

Insights

The 15th and 97th birth weight percentiles are optimal for identifying small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants, respectively. These cut-offs better predict neonatal risks than the traditional 10th and 90th percentiles.

Area of Science:

  • Perinatal epidemiology
  • Neonatal outcomes
  • Fetal growth assessment

Background:

  • Defining small-for-gestational-age (SGA) and large-for-gestational-age (LGA) is crucial for identifying infants at risk.
  • Current percentile cut-offs (10th and 90th) for SGA and LGA lack robust clinical validation.

Purpose of the Study:

  • To evaluate and determine optimal birth weight percentile cut-offs for defining SGA and LGA.
  • To assess the clinical significance of different percentile cut-offs in relation to neonatal outcomes.

Main Methods:

  • Analysis of a large US birth cohort (17,979,120 singleton live births, 1995-2001).
  • Comparison of neonatal death and low 5-min Apgar scores (reference: 25th-75th percentile).
  • Calculation of risk ratios (RR) for SGA and LGA infants versus the reference group.

Main Results:

  • The 15th percentile identified SGA infants with >2-fold risk of neonatal death across gestational ages (except <28 weeks).
  • The 97th percentile identified LGA infants with a 2-fold risk of low 5-min Apgar at term.
  • LGA was linked to reduced low Apgar risk preterm but increased risk at term/post-term.

Conclusions:

  • The 10th and 90th percentiles for SGA and LGA are likely arbitrary.
  • The 15th and 97th percentiles appear to be optimal cut-offs for defining SGA and LGA, respectively.
  • These refined cut-offs can improve the identification of infants at risk for adverse neonatal outcomes.
Abstract

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