Abstract
Background: Early life growth pattern has been linked with linear growth faltering and the occurrence of noncommunicable diseases in later life. For the past decades, low birth weight has been identified as a predictor of linear growth failure. Extremes of birth weight and its gain during infancy have been linked with subsequent body composition (bc) changes and chronic disease later in life. Weight measurements, however, do not differentiate between fat mass (fm) and fat-free mass (ffm) of the child. Although early life factors expressed in simple anthropometric measurements have been well explored, to the best of our knowledge, none of the earlier studies tried to investigate what mediates the link between birth weight and its gain during infancy with linear growth and bc during childhood.
Objectives: The objective of this study was to explore the association between prenatal bc (birth bc) and early infancy bc with childhood linear growth. Further, we explored the role of early infancy bc changes on childhood bc.
Methods: Data were collected from 644 mother-infant pairs who were enrolled in the infant anthropometry and body composition (iabc) birth cohort at jimma university specialized hospital, jimma, ethiopia. Data on household socio-demographic and economic characteristics, dietary history and morbidity were collected through interview administered questionnaire. Height-for-age z-score (haz) was computed using who standards. An air-displacement plethysmography (adp) was used to measure fm and ffm during early infancy, and at the age of 4 years. Maternal weight and height were measured within 48 hours after delivery and on subsequent visit during postnatal period. Multivariable linear regression was done to explore association between birth bc and haz at 2 years. Linear mixed effects model was used to investigate the relation between bc in early infancy and linear growth during childhood. Furthermore, the association between bc in early infancy with bc at 4 years was explored using multivariable linear regression model.
Results: In paper one, we used birth and 2 years data from 268 children to explore the relation between bc at birth and height at 2 years, operationalized as height-for-age z-score (haz). A quarter (26%) of the children were stunted (haz < -2) at 2 years. Birth ffm was an independent positive predictor of haz at 2 years; it increased by 0.73 (95% ci: 0.08, 1.38) for each kg ffm increment at birth. Nevertheless, birth fm was not associated with haz at 2 years.
Paper two presents analysis of association between fm and ffm accretion during early infancy with linear growth from 1 to 5 years. Data from 354 children who were followed from birth to 5 years of age was analyzed. Positive association was found between ffm accretion from birth to 6 months and linear growth from 1 to 5 years ( = 0.63; 95% ci: 0.19, 1.07). This association was independent of length accretion and other confounders adjusted for. Fm accretion from birth to 4 months showed positive association with linear growth only after controlling for potential confounders (=0.45; 95% ci: 0.02, 0.88). Further, ffm but not fm at birth predicted linear growth from 1 to 5 years.
The third paper looked at the association between bc at birth and early infancy with bc at 4 years. Ffm both at birth (=1.07; 95% ci 0.60, 1.55) and from birth to 6 months (=0.24; 95% ci 0.11, 0.36) positively predicted ffm index (ffmi) at 4 years. Fm at birth (=1.17; 95% ci 0.13, 2.22) and from birth to 4 months (=0.21; 95% ci 0.00, 0.42) were positively associated with fm index (fmi) at 4 years. Ffm accretion during early infancy had positive association (=0.20; 95% ci 0.04, 0.37) with fmi at the age of 4 years. However, fm at birth and its accretion during infancy did not predict ffmi at 4 years.
Conclusions: Identifying early life risk factors of linear growth and body composition are crucial to reduce the short- and long-term health consequences of undernutrition in early life. In general, the findings included in this thesis revealed that higher ffm at birth and during early infancy predicted an increased linear growth and higher ffm during childhoods which are known to be associated with better health outcomes. Both higher fm at birth and during early infancy predicted higher fm during childhood. In addition, accretion of ffm in early infancy correlated with fm at 4 years of age, while accretion of fm correlated positively with linear growth. This study warrants xii further research from the same or similar cohort to investigate whether these associations persist if we use bc assessed from birth to childhood with later health outcomes.
| Original language | English |
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| Place of Publication | Copenhagen |
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| Publisher | Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen |
| Number of pages | 169 |
| ISBN (Print) | 978-87-7209-197-6 |
| Publication status | Published - 2018 |