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Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Improving the accuracy of weight status assessment in infancy research
Wallace E Dixon1, William T Dalton1, Sarah M Berry1
1Department of Psychology, East Tennessee State University, United States.
Insights
Comparing infant weight status assessments, recumbent length measurements yielded higher weight-for-length z-scores (WLZ) than standing height at 18 months. Recumbent length WLZ scores also decreased significantly by 21 months, unlike standing height measures.
Area of Science:
- Pediatric Nutrition
- Growth Monitoring
- Infant Health Assessment
Background:
- Variability exists in infant weight status assessment methods among researchers and clinicians.
- Accurate growth monitoring is crucial for identifying potential health issues in infants.
Purpose of the Study:
- To compare weight-for-length z-score (WLZ) derivation using standing height versus recumbent length in infants.
- To evaluate the impact of measurement method on WLZ scores at 18 and 21 months using WHO growth curves.
Main Methods:
- A convenience sample of 58 infants was assessed at 18 months, with 45 returning at 21 months.
- Weight-for-length z-scores were calculated using both standing-height and recumbent-length measurements.
- Data were analyzed using WHO growth curves.
Main Results:
- Recumbent-length-derived WLZ scores were significantly higher than standing-height-derived WLZ scores at 18 months.
- Recumbent-length-derived WLZ scores showed a significant decrease from 18 to 21 months, while standing-height-derived scores did not.
- Observed differences are partly attributed to WHO database syntax automatically adjusting standing height measurements.
Conclusions:
- Measurement method (standing height vs. recumbent length) impacts infant WLZ scores.
- For practical application, using standing height measurements entered as recumbent length into the WHO database may be preferred.
- Researchers are encouraged to incorporate BMI assessments into routine infant studies for potential outcome measures.
Abstract:
Both researchers and primary care providers vary in their methods for assessing weight status in infants. The purpose of the present investigation was to compare standing-height-derived to recumbent-length-derived weight-for-length standardized (WLZ) scores, using the WHO growth curves, in a convenience sample of infants who visited the lab at 18 and 21 months of age. Fifty-eight primarily White, middle class infants (25 girls) from a semi-rural region of southern Appalachia visited the lab at 18 months, with 45 infants returning 3 months later. We found that recumbent-length-derived WLZ scores were significantly higher at 18 months than corresponding standing-height-derived WLZ scores. We also found that recumbent-length-derived WLZ scores, but not those derived from standing height measures, decreased significantly from 18 to 21 months. Although these differential results are attributable to the WHO database data entry syntax, which automatically corrects standing height measurements by adding 0.7 cm, they suggest that researchers proceed cautiously when using standing-height derived measures when calculating infant BMI z-scores. Our results suggest that for practical purposes, standing height measurements may be preferred, so long as they are entered into the WHO database as recumbent length measurements. We also encourage basic science infancy researchers to include BMI assessments as part of their routine assessment protocols, to serve as potential outcome measures for other basic science variables of theoretical interest.
