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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.)

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.