Table 5 Adjusted OR for pre-school asthma vs controls in relation to the number of hours spent in swimming pools before asthma onset (Unexposed as reference)

1y (n = 153)

(1.39

3.65)

(1.08

2.76)

(1.33

2.86)

2y (n = 93)

(1.10

3.16)

(0.94

3.25)

(1.14

2.90)

3y (n = 72)

(1.01

3.29)

(0.75

2.91)

(0.98

2.86)

4y (n = 55)

(0.63

2.40)

(0.53

2.42)

(0.65

2.20)

5y (n = 39)

(0.38

2.07)

(0.64

3.56)

(0.53

2.39)

6y (n = 26)

(0.31

2.78)

(0.29

3.09)

(0.34

2.65)