Agnes M. M. Sonnenschein-van der Voort, Lidia R. Arends, Johan C. de Jongste, Isabella Annesi-Maesano, S. Hasan Arshad, Henrique Barros, Mikel Basterrechea, Hans Bisgaard, Leda Chatzi, Eva Corpeleijn, Sofia Correia, Leone C. Craig, Graham Devereux, Cristian Dogaru, Miroslav Dostal, Karel Duchen, Merete Eggesbø, C. Kors van der Ent, Maria P. Fantini, Francesco Forastiere, Urs Frey, Ulrike Gehring, Davide Gori, Anne C. van der Gugten, Wojciech Hanke, A. John Henderson, Barbara Heude, Carmen Iñiguez, Hazel M. Inskip, Thomas Keil, Cecily C. Kelleher, Manolis Kogevinas, Eskil Kreiner-Møller, Claudia E. Kuehni, Leanne K. Küpers, Kinga Lancz, Pernille S. Larsen, Susanne Lau, Johnny Ludvigsson, Monique Mommers, Anne-Marie Nybo Andersen, Lubica Palkovicova, Katherine C. Pike, Constanza Pizzi, Kinga Polanska, Daniela Porta, Lorenzo Richiardi, Graham Roberts, Anne Schmidt, Radim J. Sram, Jordi Sunyer, Carel Thijs, Maties Torrent, Karien Viljoen, Alet H. Wijga, Martine Vrijheid, Vincent W. V. Jaddoe, Liesbeth Duijts

• 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-effectBackground 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."…