Methods
This study is a population-based birth cohort study conducted during July 2015 and July 2019 at King Chulalongkorn Memorial Hospital (KCMH), in Bangkok, Thailand. Pregnant women with 27th to 36th week of gestation who was living in Bangkok and visited KCMH between July 2015 to January 2016 were invited to join our study. The inclusion criteria were healthy full-term infants who were born from low risk healthy pregnant women. Infants born from multiple pregnancies or high-risk pregnant women, preterm infants and infants with congenital anomalies were excluded. Informed consent was obtained from all parents. Overall, 600 women were screened, 500 mother-children pairs were eligible to the inclusion criteria in which 369 pairs were enrolled. We performed longitudinal assessments of the subjects from the third trimester of pregnancy until the child reached 30 months of age. The study was performed according to the Helsinki Guidelines and approved by the Ethics Committee of KCMH (IRB No. 358/58). Details of clinical data collection, definition of allergic diseases, methods to define sensitization to food allergens and aeroallergens were described in the Appendix.
Statistical analysis
The statistical analysis was performed by IBM SPSS Statistics for Windows, version 22 (IBM Corp., Armonk, N.Y., USA). Characteristics of the patients were presented using the median (range) for continuous data or the number and percentage for categorical data. Associations between factors including aeroallergen sensitization and allergic diseases were estimated using univariate and multivariable logistic regression which represented in odds ratio and 95% confidence intervals (CI). Cox proportional hazard regression was used to find factors associated with outgrown of allergic disease, which represented in hazard ratio and 95% confidence intervals (CI). Adjustments were made for potential confounders. Kaplan-Meier curves were generated to depict the development of outgrown of allergic diseases over time.