Background: Recurrent wheezing (RW) plays an important role in the morbidity and mortality of children during the first year of life in developing regions and its actual incidence in those areas is virtually unknown.
Methods and results: This study describes the occurrence of wheezing during the first year of life in a birth cohort of 188 infants followed monthly and living in a poor urban area in Santiago de Chile. This study showed that 80.3 % of the infants in the cohort had one or more wheezing episode during the first year of life, 43.1 % had RW (3 or more wheezing episodes), 44.1 % had their first wheezing within the first three months of life and 13.3 % had pneumonia (PN). Having one or more episode of wheezing in the first three months of life was the main risk factor for suffering from RW during the first year and RW was a significant risk factor for having PN.
Conclusions: This study found a high prevalence of RW in infants from a low-income population during the first year of life with the disease starting very early in their lives, progressing with more frequent episodes and being significantly associated to PN, particularly in the first 6 months of life.