Joint effects of birth outcomes and childhood body mass index on respiratory symptoms. Eur Respir J 2012: 39: 1213–9. Supporting Information Additional Supporting Information may be found in the online version of this article

Thinness in infancy and higher childhood body-mass index (BMI) are risk factors for poor respiratory health. However, few study has examined the joint effects of birth outcomes and childhood BM I on the occurrence of respiratory symptoms. A total of 78,011 Taiwanese middle-school children were investigated between 1995 and 1996 in a nationwide International Study of Asthma and Allergies in Childhood (ISAAC) survey, with standardized height/weight measurement. Their survey data was successfully compared with the birth registration dataset. Childhood BMI was positively associated with all respiratory symptoms, with greater effects and significant risks on serious phenotypes in the video questionnaire. Children with a history of low birth weight (LBW), those who were born prematurely (preterm), or those who were small for gestational age (SGA) were also more likely to have allergic respiratory symptoms. Since birthweight and gestational age were not positively associated with childhood BMI, we proposed that LBW, preterm birth and childhood BMI were independent factors for respiratory symptoms. LBW, preterm birth and childhood BMI are all independent risk factors for respiratory symptom