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Updated: Jun 21, 2026
09:29
Skeletal Muscle Gender Dimorphism from Proteomics
Published on: December 14, 2011
Sex differences in body composition early in life.
David A Fields1, Sowmya Krishnan, Amy B Wisniewski
1Department of Pediatrics Section of Endocrinology and Diabetes, Children's Medical Research Institute's Diabetes & Metabolic Research Program, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73117, USA. dfields@ouhsc.edu
Gender Medicine
|August 18, 2009
Summary
Sex differences in infant body composition, including percent fat and fat-free mass, were observed at 1 month but resolved by 6 months of age in healthy newborns.
Area of Science:
- Pediatric medicine
- Human development
- Body composition analysis
Background:
- Early body composition is crucial for long-term health, with excessive fat linked to diabetes and other morbidities.
- Limited data exist on sex differences in infant body composition during the first months of life.
Purpose of the Study:
- To investigate if sex differences in body composition observed at birth persist through the first six months of life.
Main Methods:
- Healthy, full-term newborns (male and female) were enrolled.
- Body composition (% fat, total fat, fat-free mass) was measured using whole body plethysmography at approximately 1, 3, and 6 months of age.
- Inclusion criteria ensured healthy mothers and infants, excluding those with specific pregnancy complications or birth defects.
Main Results:
- At birth, girls were shorter and weighed more than boys (P < 0.05).
- At ~1 month, girls had significantly higher %fat (15.1% vs 12.7%) and lower fat-free mass (P < 0.001) than boys.
- By 6 months of age, no significant sex differences in body composition variables were observed.
Conclusions:
- Statistically significant sex differences in %fat and fat-free mass exist in newborns around 1 month of age.
- These body composition differences between sexes diminish and are no longer significant by 6 months of age in healthy infants.
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