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.