Objective assessment of levels and patterns of physical activity in preschool children.

BACKGROUND: The aim of this study was to examine in detail levels and patterns of physical activity in preschool children and the effects of gender and BMI on this activity. METHODS: Two hundred and fifty-three children aged 5 y participating in the Copenhagen Prospective Studies on Asthma in Childhood wore an accelerometer day and night over a 4-wk period. The main outcome measure was level of physical activity using the raw data. A secondary measure was time spent in moderate to vigorous physical activity (MVPA). A Fourier series analysis was applied to study in detail patterns over time. RESULTS: Activity profiles throughout the year were unique for each sex, with boys being overall more active than girls except for winter months. Preschool children also showed distinct patterns of physical activity during weekdays as compared with weekends and were most active during weekdays. Preschool children in the highest tertile of BMI had a flat yearly activity profile and tended to be less active as compared with those in the lowest tertile. CONCLUSION: Preschool children showed significant gender differences in physical activity, with distinct patterns throughout the year as well as between weekdays and weekends. A high BMI tended to be associated with lower levels of physical activity.

Polyunsaturated fatty acid content of mother's milk is associated with childhood body composition.

BACKGROUND: The consumption of polyunsaturated fatty acids has changed, and the prevalence of adiposity has increased over the past 30 y. A decrease of n-3 polyunsaturated fatty acid content in breast milk has been suggested to be a contributing factor. The objective of this study was to investigate the relationship between docosahexaenoic acid (DHA) content and n-6/n-3 polyunsaturated fatty acid ratio in breast milk, body composition, and timing of adiposity rebound in children. METHODS: In the Copenhagen Prospective Study on Asthma in Childhood birth cohort, breast milk fatty acid profile was determined in 281 mothers and BMI development was prospectively followed up to the age of 7 y in 222 children. Age and BMI at adiposity rebound were registered. Furthermore, fat mass determination by dual energy X-ray absorptiometry was performed in 207 children at 6-9 y of age. RESULTS: There was a significant association between breast milk DHA and BMI from 2 to 7 y, fat mass, and, for the girls, age at adiposity rebound. No associations were found between the breast milk n-6/n-3 polyunsaturated fatty acid ratio and body composition. CONCLUSION: Early intake of DHA may have an effect on body composition. Dietary habits of lactating mothers could contribute to the increased prevalence of obesity in Western societies.

Physical activity in young children is reduced with increasing bronchial responsiveness.

BACKGROUND: Physical activity is essential for young children to develop adequately and for quality of life. It can be lower in children with subclinical asthma, and therefore methods to reveal subclinical reduction in physical activity in young children are warranted. OBJECTIVE: We sought to study an association between physical activity in preschool children and objectively assessed intermediary asthma phenotypes. METHODS: We studied 253 five-year-old children (127 girls) participating in the Copenhagen Prospective Studies on Asthma in Childhood. The main outcome measure was level of physical activity assessed objectively with accelerometers worn on an ankle for 4 weeks. Objective assessment of asthma intermediary phenotypes included prebronchodilator and postbronchodilator specific airway resistance, bronchial responsiveness to cold dry-air hyperventilation, and exhaled nitric oxide levels. Analyses were performed with generalized linear model and principal component analysis. RESULTS: Physical activity was inversely associated with bronchial responsiveness (relative rate, 0.89; 95% CI, 0.83-0.95; P = .007) and significantly increased in the months of spring and summer (P < .001) and in boys (relative rate, 1.16; 95% CI, 1.09-1.25; P < .001). Physical activity was independent of asthma diagnosis, age, body mass index, baseline specific airway resistance, reversibility to beta(2)-agonist, sensitization, and exhaled nitric oxide level. CONCLUSION: Physical activity in preschool children was reduced with increasing bronchial responsiveness. The reduced physical activity was subclinical and not realized by parents or doctors despite daily diary cards and close clinical follow-up since birth. This observation warrants awareness of even very mild asthma symptoms in clinical practice.

Childhood asthma after bacterial colonization of the airway in neonates.

BACKGROUND: Pathological features of the airway in young children with severe recurrent wheeze suggest an association between bacterial colonization and the initiating events of early asthma. We conducted a study to investigate a possible association between bacterial colonization of the hypopharynx in asymptomatic neonates and later development of recurrent wheeze, asthma, and allergy during the first 5 years of life. METHODS: The subjects were children from the Copenhagen Prospective Study on Asthma in Childhood birth cohort who were born to mothers with asthma. Aspirates from the hypopharyngeal region of asymptomatic 1-month-old infants were cultured for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Wheeze was monitored prospectively on diary cards during the first 5 years of life. Blood eosinophil count and total IgE and specific IgE were measured at 4 years of age. Lung function was measured and asthma was diagnosed at 5 years of age. RESULTS: Hypopharyngeal samples were cultured from 321 neonates at 1 month of age. Twenty-one percent of the infants were colonized with S. pneumoniae, M. catarrhalis, H. influenzae, or a combination of these organisms; colonization with one or more of these organisms, but not colonization with S. aureus, was significantly associated with persistent wheeze (hazard ratio, 2.40; 95% confidence interval [CI], 1.45 to 3.99), acute severe exacerbation of wheeze (hazard ratio, 2.99; 95% CI, 1.66 to 5.39), and hospitalization for wheeze (hazard ratio, 3.85; 95% CI, 1.90 to 7.79). Blood eosinophil counts and total IgE at 4 years of age were significantly increased in children colonized neonatally with S. pneumoniae, M. catarrhalis, H. influenzae, or a combination of these organisms, but specific IgE was not significantly affected. The prevalence of asthma and the reversibility of airway resistance after beta2-agonist administration at 5 years of age were significantly increased in the children colonized neonatally with these organisms as compared with the children without such colonization (33% vs. 10% and 23% vs. 18%, respectively). CONCLUSIONS: Neonates colonized in the hypopharyngeal region with S. pneumoniae, H. influenzae, or M. catarrhalis, or with a combination of these organisms, are at increased risk for recurrent wheeze and asthma early in life.

Chromosome 17q21 gene variants are associated with asthma and exacerbations but not atopy in early childhood.

RATIONALE: An asthma predisposition locus on chromosome 17q12-q21 has recently been replicated in different ethnic groups. OBJECTIVES: To characterize the asthma and atopy phenotypes in early childhood that associate with the 17q12-21 locus. METHODS: The single nucleotide polymorphism (SNP), rs7216389, was genotyped in 376 of 411 children from the Copenhagen Prospective Study on Asthma in Childhood (COPSAC) birth cohort born to mothers with asthma together with 305 mothers and 224 fathers. Nineteen additional SNPs in the region were genotyped in the children. Investigator-diagnosed clinical endpoints were based on diary cards and clinic visits every 6 months and at acute symptoms from birth. Lung function, bronchial responsiveness, and sensitization were tested longitudinally from early infancy. MEASUREMENTS AND MAIN RESULTS: rs7216389 was significantly associated with the development of wheeze (hazard ratio 1.64 [1.05-2.59], P value = 0.03), asthma (hazard ratio, 1.88 [1.15-3.07], P = 0.01), and acute severe exacerbations (hazard ratio 2.66 [1.58-4.48], P value = 0.0002). The effect on wheeze and asthma was observed for early onset but not late onset of disease. The increased risk of exacerbations persisted from 1 to 6 years of age (incidence ratio 2.48 [1.42-4.32], P value = 0.001), and increased bronchial responsiveness was present in infancy and at 4 years of age, but not at 6 years. In contrast, rs7216389 conferred no risk of eczema, rhinitis, or allergic sensitization. CONCLUSIONS: Variation at the chromosome 17q12-q21 locus was associated with approximately twofold increased risk of recurrent wheeze, asthma, asthma exacerbations, and bronchial hyperresponsiveness from early infancy to school age but without conferring risk of eczema, rhinitis, or allergic sensitization. These longitudinal clinical data show this locus to be an important genetic determinant of nonatopic asthma in children.