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Gender- and gestational age-specific body fat percentage at birth
Colin P Hawkes1, Jonathan O'B Hourihane, Louise C Kenny
1Department of Paediatrics and Child Health, University College Cork, Cork, Ireland.
Insights
Newborn body fat percentage (%BF) increases with gestational age and differs by gender. This study provides crucial reference values for neonatal adiposity, essential for assessing infant health and development.
Area of Science:
- Neonatal physiology
- Pediatric health assessment
- Body composition analysis
Background:
- In utero growth significantly impacts lifelong health, with birth weight and length being common but limited indicators.
- Neonatal adiposity is not well-reflected by traditional birth measurements.
- Air-displacement plethysmography offers a validated method for precise body fat measurement in newborns.
Purpose of the Study:
- To establish normal reference values for neonatal percentage body fat (%BF) within the first four days of life.
- To provide a normative dataset for %BF in infants.
Main Methods:
- Utilized air-displacement plethysmography to measure fat mass, fat-free mass, and %BF in a large birth cohort.
- Infants were analyzed within the first four days post-birth.
- Data were stratified by gestational age and infant gender.
Main Results:
- Measurements were successfully obtained from 743 of 786 infants (94.5%).
- %BF showed a significant positive correlation with gestational age, increasing from 8.9% at 36-37 weeks to 11.2% at 40-41 weeks.
- Female infants exhibited higher %BF than males at later gestational ages (e.g., 12.5% vs. 10% at 40-41 weeks).
Conclusions:
- Gestational age and gender are significant determinants of neonatal %BF.
- Accurate, population-based centiles for neonatal %BF were successfully generated, offering a valuable clinical reference tool.
Background:
There is increasing evidence that in utero growth has both immediate and far-reaching influence on health. Birth weight and length are used as surrogate measures of in utero growth. However, these measures poorly reflect neonatal adiposity. Air-displacement plethysmography has been validated for the measurement of body fat in the neonatal population.
Objective:
The goal of this study was to show the normal reference values of percentage body fat (%BF) in infants during the first 4 days of life.
Methods:
As part of a large population-based birth cohort study, fat mass, fat-free mass, and %BF were measured within the first 4 days of life using air-displacement plethsymography. Infants were grouped into gestational age and gender categories.
Results:
Of the 786 enrolled infants, fat mass, fat-free mass, and %BF were measured in 743 (94.5%) infants within the first 4 days of life. %BF increased significantly with gestational age. Mean (SD) %BF at 36 to 37⁶/⁷ weeks' gestation was 8.9% (3.5%); at 38 to 39 weeks' gestation, 10.3% (4%); and at 40 to 41⁶/⁷ weeks' gestation, 11.2% (4.3%) (P < .001). Female infants had significantly increased mean (SD) %BF at 38 to 39⁶/⁷ (11.1% [3.9%] vs 9.8% [3.9%]; P = .012) and at 40 to 41⁶/⁷ (12.5% [4.4%] vs 10% [3.9%]; P < .001) weeks' gestation compared with male infants. Gender- and gestational age-specific centiles were calculated, and a normative table was generated for reference.
Conclusion:
%BF at birth is influenced by gestational age and gender. We generated accurate %BF centiles from a large population-based cohort.
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