Table 3 The association between demographic variables and body mass index by gender at baseline

Boys (No. of subjects)

307

1327

276

296

Breastfeeding (%)

0.74

No

56.4

58.6

56.9

59.5

≤ 1 month

20.5

17.1

15.9

16.2

> 1 month

23.1

24.3

27.2

24.3

Regular exercise (%)

< 0.001

Seldom

6.5

9.0

5.8

12.8

Sometimes

40.7

35.7

40.6

46.3

Regularly

52.8

55.3

53.6

40.9

Air conditioning (yes, %)

87.6

89.0

89.9

93.9

0.06

Cigarette smoking (yes, %)

12.4

8.1

8.3

10.1

0.17

Exposure to ETS (yes, %)

53.8

56.0

55.8

63.5

0.07

Mould/Fungal at home (yes, %)

27.0

28.2

27.5

28.7

0.97

Parental history of asthma (yes, %)

2.3

3.5

2.2

3.7

0.41

Parent education (%)

0.03

≤ 9 yrs

41.7

32.5

29.7

35.1

10 - 12 yrs

29.0

36.5

34.4

34.1

≥ 13 yrs

29.3

31.1

35.9

30.7

Pet (yes,%)

30.6

25.5

22.1

30.4

0.04

Girls (No. of subjects)

204

1201

251

190

Breastfeeding (%)

0.04

No

52.0

57.9

55.0

48.4

≤ 1 month

17.3

17.4

14.7

15.8

> 1 month

30.4

24.7

30.3

35.8

Regular exercise (%)

0.58

Seldom

19.6

19.1

15.5

19.0

Sometimes

59.8

57.2

63.8

59.0

Regularly

20.6

23.7

20.7

22.1

Air conditioning (yes, %)

84.8

89.2

88.1

88.4

0.43

Cigarette smoking (yes, %)

2.0

2.4

3.2

2.6

0.84

Exposure to ETS (yes, %)

52.5

58.2

59.4

60.0

0.38

Mould/Fungal at home (yes, %)

30.4

32.5

26.7

31.6

0.32

Parental history of asthma (yes, %)

5.9

4.9

5.2

4.2

0.89

Parent education (%)

0.75

≤ 9 yrs

31.4

34.3

32.7

34.7

10 - 12 yrs

37.3

35.8

40.2

39.0

≥ 13 yrs

31.4

29.9

27.1

26.3

Pet (yes,%)

27.0

27.8

31.5

34.7

0.20