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Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels
Published on: August 7, 2017
Perinatal factors and respiratory health in children
1Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia. bronwynbrew@woolcock.org.au
Insights
Low birth weight in children with a family history of asthma is linked to increased asthma risk and reduced lung function by age 8. Post-natal growth, indicated by current height, influences these associations.
Area of Science:
- Pediatric respiratory health
- Birth anthropometry and developmental origins of disease
Background:
- Conflicting evidence exists on the link between birth measurements and childhood asthma/lung function.
- Studies often lack rigorous design, potentially affecting validity.
Purpose of the Study:
- To clarify associations between anthropometric birth measures and asthma/lung function in children.
- To address limitations in previous study designs and analyses.
Main Methods:
- Analysis of a birth cohort with a family history of asthma, recruited antenatally.
- Measurement of birth anthropometrics, confounders, lung function, and asthma outcomes at 8 years.
- Assessment of airway hyperresponsiveness (AHR) and investigation of potential reversal paradox.
Main Results:
- Lowest tertile of birth weight associated with higher odds of current asthma and recent wheeze.
- Birth weight positively correlated with lung function at 8 years.
- Current height modified the birth length-lung function relationship, indicating a role for postnatal growth.
Conclusions:
- Low birth weight increases asthma risk and reduces lung function in children with a family history of asthma.
- Current height acts as an effect modifier in the context of the fetal origins hypothesis for respiratory health.
Background:
There is conflicting evidence regarding the associations between anthropometric birth measures and asthma and lung function in children, particularly for apparently healthy infants born at term.
Objective:
Our objective was to elucidate these relationships paying particular attention to features of study design and analysis that may threaten the validity of previous studies in this field.
Methods:
We analysed data from a cohort of children with a family history of asthma who were recruited antenatally. Anthropometric birth measures and potential confounders were recorded at birth and within the first year of life. Lung function and asthma outcomes were measured at 8 years of age. Airway hyperresponsiveness (AHR) was measured by methacholine challenge. The potential for a reversal paradox, due to inclusion of covariates on the causal pathway, was investigated.
Results:
Four hundred and fifty (73% of the initial cohort) children were tested at age 8 years. Birth weight in the lowest tertile was associated with current asthma (OR 1.95, 95% CI 1.08, 3.54) and recent wheeze (OR 1.87, 95%CI 1.08, 3.24), but not with AHR (OR 1.37, 95% CI 0.68, 2.78). Birth weight was positively associated with lung function. Current height modified the relationship between birth length and lung function suggesting that post-natal growth has an effect on this relationship.
Conclusions:
Low birth weight is associated with a greater risk of current asthma and lower lung function at 8 years in children with a family history of asthma. Current height should be treated as an effect modifier when investigating the fetal origins hypothesis.
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