Statistical analysis
Two groups were compared using χ2 test. The main
outcomes were asthma, allergic rhinitis/conjunctivitis, and atopic
dermatitis in children. Multivariable logistic regression was used to
estimate the adjusted odds ratios with 95% confidence intervals for the
following potential factors. Based on previous reports, the factors
related to the incidence of asthma, including daycare attendance,
existence of older siblings, a history of hospitalization owing to
cold/bronchitis/bronchiolitis/pneumonia, preterm birth, and overweight
gain were analyzed and adjusted for the potential confounders of asthma,
including sex, maternal smoking, breastfeeding, and presence of early
atopic dermatitis. We used the same factors to analyze allergic
rhinitis/conjunctivitis; in addition, to analyze atopic dermatitis, we
used the same factors mentioned barring “presence of early atopic
dermatitis.” The probability values for the statistical tests were
two-tailed, and P < 0.05 was regarded as statistically
significant. All statistical analyses were performed via JMP system
version 15 (SAS Institute Inc., Cary, NC, USA).