Day-care attendance, position in sibship, and early childhood wheezing: A population-based birth cohort study.

This study showed that day-care attendance was associated with reduced risk of current wheezing in 5-year-old children. The protective effect was strongest for children who entered day-care between 6 and 12 months. Wheeze was reported by 203 participants (22%); 224 (28%) were sensitised. Sensitisation, male sex, maternal asthma, and maternal smoking during pregnancy significantly increased the risk of wheezing. Entering day-care between 6 and 12 or after 12 months of age was inversely associated with current wheeze. Entry into nursery between 6 and 12 months reduced the risk of persistent wheezing (P = 0.04). We found no association between day-care attendance and lung function. Entering nursery in the first 6 months of life was associated with increased risk of atopy (2.47, 1.23-4.95). Having older siblings was associated only with rhinoconjunctivitis (0.72, 0.54-0.97). J Allergy Clin Immunol. 2008;122(3):500-6.