Fig. 2

Interaction between serum cotinine [low-level (< 0.0436 ng/ml) and high-level (≥ 0.0436 ng/ml) serum cotinine] and BMI [Group A underweight and normal weight (< 85th percentile); Group B: overweight (≥ 85th percentile to < 95th percentile); and Group C: obesity (≥ 95th percentile) on childhood asthma, low-level serum cotinine and Group A was the reference. OR: odds ratio; CI: confidence interval; BMI: body mass index; Model 1: unadjusted logistic model (A); Model 2: adjusted for age and gender (B); Model 3: adjusted for age, gender, ethnicity, gender of the household reference person, and marital status of the household reference person (C)