In a recent paper published in Thorax Canoy and co-workers1 concluded that babies with lower birth weight and poor infant growth may be at a higher risk of developing impaired adult pulmonary function. In contradiction to these findings, no association was found between birth weight and adult lung function or between birth weight and asthma symptoms in a Nordic-Baltic population studied by Laerum et al.2 Studies of birth characteristics and respiratory outcomes give contradictory results as methods used in different …