Kim A, et al. - Whether perinatal factors and other risk factors have an independent or combined effect on the development of asthma, was investigated herein. Two important perinatal factors that were noted to have an impact on asthma development were early life oxygen therapy and breastfeeding. Also, development of asthma was influenced by these factors in combination with other risk factors (environmental tobacco smoke, traffic-related air pollution, parental allergic disease, and atopy).