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Weight/length ratio references and newborn body composition estimation at birth from a Brazilian cohort

Carlos Grandi1, Livia Dos S Rodrigues2, Davi C Aragon2

  • 1Argentine Society of Pediatrics, Research Department, Buenos Aires, Argentina.

Jornal De Pediatria
|February 13, 2021
PubMed

Insights

This study calculated weight/length (W/L) ratios and body composition percentiles for Brazilian newborns. Results show that small-for-gestational-age (SGA) and wasted infants have lower body composition measures, informing nutritional assessments.

Area of Science:

  • Pediatrics
  • Neonatology
  • Nutritional Science

Background:

  • Accurate assessment of newborn body composition is crucial for identifying nutritional status.
  • Existing references may not fully represent diverse neonatal populations.

Purpose of the Study:

  • To establish weight/length (W/L) ratio percentiles by sex and gestational age (GA) for Brazilian newborns.
  • To estimate fat mass (FM), fat-free mass (FFM), and body fat percentage (BF%) using W/L ratios.
  • To compare body composition indices in preterm, SGA, LGA, stunted, and wasted infants with INTERGROWTH-21st standards.

Main Methods:

  • Secondary analysis of 7427 live-born infants from the BRISA Cohort Study (2010).
  • Utilized multiple regression models with W/L ratio for body composition estimation.
  • Calculated 3rd, 50th, and 97th percentiles for W/L ratio and body composition using fractional polynomial regression.

Main Results:

  • Average W/L ratio was 6.50 kg/m; average FM, BF%, and FFM were 359.64 g, 10.90%, and 2798.84 g, respectively.
  • Small-for-gestational-age (SGA) and wasted infants exhibited the lowest W/L ratios and body composition measures.
  • Presented percentile charts for W/L, FM, BF%, and FFM by GA and sex.

Conclusions:

  • Weight/length (W/L) ratio values from the RP-BRISA Cohort exceed those from INTERGROWTH-21st.
  • SGA and wasted infants demonstrate suboptimal body composition.
  • The developed body composition references can enhance nutritional assessment for Brazilian newborns and facilitate cross-population comparisons.
Abstract

Keywords:
AnthropometryBody compositionFat massNutrition assessmentWeight/length ratio

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