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Background: Children born preterm or with a small size for gestational age are at increased risk for childhood asthma., Objective: We sought to assess the hypothesis that these associations are explained by reduced airway patency., Methods: We used individual participant data of 24,938 children from 24 birth cohorts to examine and meta-analyze the associations of gestational age, size for gestational age, and infant weight gain with childhood lung function and asthma (age range, 3.9-19.1 years). Second, we explored whether these lung function outcomes mediated the associations of early growth characteristics with childhood asthma., Results: Children born with a younger gestational age had a lower FEV1, FEV1/forced vital capacity (FVC) ratio, and forced expiratory volume after exhaling 75% of vital capacity (FEF75), whereas those born with a smaller size for gestational age at birth had a lower FEV1 but higher FEV1/FVC ratio (P < .05). Greater infant weight gain was associated with higher FEV1 but lower FEV1/FVC ratio and FEF75 in childhood (P < .05). All associations were present across the full range and independent of other early-life growth characteristics. Preterm birth, low birth weight, and greater infant weight gain were associated with an increased risk of childhood asthma (pooled odds ratio, 1.34 [95% CI, 1.15-1.57], 1.32 [95% CI, 1.07-1.62], and 1.27 [95% CI, 1.21-1.34], respectively). Mediation analyses suggested that FEV1, FEV1/FVC ratio, and FEF75 might explain 7% (95% CI, 2% to 10%) to 45% (95% CI, 15% to 81%) of the associations between early growth characteristics and asthma., Conclusions: Younger gestational age, smaller size for gestational age, and greater infant weight gain were across the full ranges associated with childhood lung function. These associations explain the risk of childhood asthma to a substantial extent., (Copyright © 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Preterm birth, low birth weight, and infant catch-up growth seem associated with an increased risk of respiratory diseases in later life, but individual studies showed conflicting results., Objectives: We performed an individual participant data meta-analysis for 147,252 children of 31 birth cohort studies to determine the associations of birth and infant growth characteristics with the risks of preschool wheezing (1-4 years) and school-age asthma (5-10 years)., Methods: First, we performed an adjusted 1-stage random-effect meta-analysis to assess the combined associations of gestational age, birth weight, and infant weight gain with childhood asthma. Second, we performed an adjusted 2-stage random-effect meta-analysis to assess the associations of preterm birth (gestational age <37 weeks) and low birth weight (<2500 g) with childhood asthma outcomes., Results: Younger gestational age at birth and higher infant weight gain were independently associated with higher risks of preschool wheezing and school-age asthma (P < .05). The inverse associations of birth weight with childhood asthma were explained by gestational age at birth. Compared with term-born children with normal infant weight gain, we observed the highest risks of school-age asthma in children born preterm with high infant weight gain (odds ratio [OR], 4.47; 95% CI, 2.58-7.76). Preterm birth was positively associated with an increased risk of preschool wheezing (pooled odds ratio [pOR], 1.34; 95% CI, 1.25-1.43) and school-age asthma (pOR, 1.40; 95% CI, 1.18-1.67) independent of birth weight. Weaker effect estimates were observed for the associations of low birth weight adjusted for gestational age at birth with preschool wheezing (pOR, 1.10; 95% CI, 1.00-1.21) and school-age asthma (pOR, 1.13; 95% CI, 1.01-1.27)., Conclusion: Younger gestational age at birth and higher infant weight gain were associated with childhood asthma outcomes. The associations of lower birth weight with childhood asthma were largely explained by gestational age at birth., (Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Objectives: Human rhinoviruses (HRVs) have been suggested to play a role in the development of childhood wheezing. However, whether HRV is causally related to the development of wheezing or HRV-associated wheeze is merely an indicator of disease susceptibility is unclear. Our aim was to study the role of HRV during infancy in the development of lower respiratory disease during infancy and childhood., Methods: In a population-based birth cohort, during the 1st year of life, nose and throat swabs were collected on a monthly basis, regardless of any symptoms. Polymerase chain reaction was used to detect an extensive panel of respiratory pathogens. Lung function was measured before 2 months of age. Information on respiratory symptoms was collected by daily questionnaires and electronic patient files., Results: 1425 samples were collected in 140 infants. Both the presence of (single or multiple) pathogens (HRV equal to other pathogens) and increased respiratory system resistance were significantly associated with lower respiratory symptoms during infancy. HRV presence during infancy was not associated with the risk of wheezing at age 4, but every HRV episode with wheezing increased the risk of wheezing at age 4 (odds ratio 1.9, 1.1-3.5). This association weakened after adjustment for lung function (odds ratio 1.4, 0.7-2.9)., Conclusions: HRV and other viruses are associated with lower respiratory symptoms during infancy, as well as a high presymptomatic respiratory system resistance. HRV presence during infancy is not associated with childhood wheezing, but wheeze during a HRV episode is an indicator of children at high risk for childhood wheeze, partly because of a reduced neonatal lung function.

Studies of reduced neonatal lung function and wheezing illnesses during childhood show conflicting results. The aim of our study was to assess the association between resistance (Rrs) and compliance (Crs) of the respiratory system by using the single occlusion technique (SOT) and prospectively collected wheezing illnesses during the first 5 years of life in a large birth cohort. SOT was performed during natural sleep before the age of 2 months. Information about wheezing illnesses was collected from the electronic patient file. 549 infants had a successful SOT measurement and complete medical records. Every kPa·L(-1)·s(-1) increase in Rrs was associated with 10% more consultations in the first 3 years of life. Every 10 mL·kPa(-1) increase in Crs was associated with a 14% reduction in consultations in the first 3 years of life, 27% in the fourth to fifth years of life, and a lower probability of having asthma at the age of 5 years (OR 0.66). Children with late-onset or persistent wheezing had significant lower Crs values than their peers. An increased neonatal resistance is associated with more wheezing illnesses during infancy, while a reduced neonatal compliance is associated with more wheezing illnesses during the first 5 years of life, a late-onset or persistent wheezing phenotype, and asthma.

The aim of our study was to investigate the association between rapid weight gain in the first 3 months of life and the prevalence of wheeze in the first years of life and lung function at 5 yrs of age. The infants selected were participating in an ongoing birth cohort. Information on growth and respiratory symptoms was collected during the first year of life, and on primary care consultations during total follow-up. Forced expiratory volume in 1 s (FEV(1)) and forced expiratory flow at 25-75% of forced vital capacity (FEF(25-75%)) were measured at 5 yrs of age. Information on growth and respiratory symptoms was obtained for 1,431 infants, out of whom 235 children had already had 5 yrs of follow-up. Every one-point z-score increase in weight gain resulted in a 37% increase in days with wheeze (incidence rate ratio 1.37, 95% CI 1.27-1.47; p<0.001) and in associated consultations by 16% (incidence rate ratio 1.16, 95% CI 1.01-1.34; p=0.04). Children with rapid weight gain reported significantly more physician-diagnosed asthma. FEV(1) and FEF(25-75%) were reduced by 34 mL (adjusted regression coefficient -0.034, 95% CI -0.056- -0.013; p=0.002) and 82 mL (adjusted regression coefficient -0.082, 95% CI -0.140- -0.024; p=0.006) per every one-point z-score increase in weight gain, respectively. These associations were independent of birthweight. Rapid early weight gain is a risk factor for clinically relevant wheezing illnesses in the first years of life and lower lung function in childhood.