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Factors influencing body composition of premature infants at term-adjusted age
S A Atkinson1, J Randall-Simpson
1Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada. satkins@fhs.mcmaster.ca
Insights
Nutrient-enriched formula improved bone mineral content (BMC) in low-birth-weight infants. Early growth and body composition are influenced by birth size and diet, with long-term effects needing further study.
Area of Science:
- Pediatrics
- Neonatology
- Nutritional Science
Background:
- Low-birth-weight (LBW) infants exhibit altered growth patterns compared to term-born infants.
- Body composition, including bone mineral content (BMC), lean mass, and fat mass, is a critical indicator of infant health and development.
- Dietary interventions post-discharge significantly impact the growth trajectory of LBW infants.
Purpose of the Study:
- To investigate the impact of birth size and infant feeding (mother's milk, standard formula, or enriched formula) on growth and body composition in LBW infants.
- To compare the whole body bone mineral content (BMC), lean mass, and fat mass of LBW infants to those of term-born infants.
- To evaluate the effectiveness of nutrient-enriched formula in improving body composition parameters in LBW infants.
Main Methods:
- Dual-energy X-ray absorptiometry (DXA) was used to assess whole body BMC, lean mass, and fat mass.
- LBW infants were categorized based on birth size (appropriate for gestational age vs. small for gestational age).
- Infant feeding regimens included mother's milk, standard formula, and energy- or nutrient-enriched formula.
Main Results:
- LBW infants appropriate for gestational age were lighter and shorter than term infants but had higher fat mass percentages.
- Infants fed standard formula or mother's milk had significantly lower BMC compared to term infants.
- LBW infants fed a nutrient-enriched formula exhibited BMC levels closer to those of term infants.
- Infants born small for gestational age had lower percent body fat and BMC compared to appropriate-for-gestational-age LBW infants of similar birth weight.
Conclusions:
- Both birth size and early-life diet are crucial determinants of growth and body composition in very-low-birth-weight (VLBW) infants.
- Nutrient-enriched formulas show promise in optimizing body composition, particularly BMC, in LBW infants.
- The long-term health implications of altered early growth patterns in VLBW infants warrant further investigation.
Abstract:
We investigated the influence of body size at birth, feeding of mother's milk versus formula, or standard-term formula versus energy- or nutrient-enriched formula on the growth and whole body bone mineral content (BMC), lean and fat mass (using dual-energy X-ray absorptiometry) of low-birth-weight (LBW) infants to term-adjusted age. LBW infants who were appropriate for gestational age were lighter and shorter than term-born infants (n = 46) but had a higher percent fat mass (19-28% vs. 15 +/- 7%). For LBW infants fed standard formula or mother's milk after hospital discharge, the mean BMC expressed either as a function of weight (17 +/- 2, 19 +/- 2 vs. 20 +/- 2 g/kg) or length (1.1 +/- 0.2, 1.1 +/- 0.2 vs. 1.5 +/- 0.2 g/cm) was more than 1 SD below term infant values. However, infants fed a nutrient-enriched formula from hospital discharge had BMC within 1 SD below term infants. Infants who were born small, compared to appropriate for gestational age, compared to infants of similar birth weight had lower percent body fat (16 +/- 6 vs. 19 +/- 5) and lower BMC (47 +/- 3 vs. 62 +/- 5 g) at term age. Both size at birth and diet influence patterns of growth and body composition in early life in very-low-birth-weight (VLBW) infants. The long-term significance of these variable growth patterns in VLBW infants in early life requires further investigation.