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Table 2 Percentage distribution of values of each factor in each group of children, with chi-square tests of association

From: Influence of maternal and perinatal factors on subsequent hospitalisation for asthma in children: evidence from the Oxford record linkage study

 

% of each group of children

Chi2 (df), with p value below

 

All asthma

(N = 4017)

Asthma, aged 0-1

(N = 535)

Asthma, aged 2+

(N = 3482)

No asthma

(N = 244595)

All asthma

Asthma aged 0-1

Asthma aged 2+

Maternal asthma:

       

No

92.0

91.0

92.2

97.6

495.6(1)

96.2(1)

409.1(1)

Yes

8.0

9.0

7.8

2.4

0.0001

<0.0001

0.0001

Total

100

100

100

100

   

Year of birth:

       

1970-1974

18.9

4.1

21.1

27.9

200.4(3)

497.9 (3)

94.1(3)

1975-1979

21.7

7.7

23.8

22.7

<0.0001

<0.0001

0.0001

1980-1984

28.4

23.2

29.2

24.2

   

1985-1989

31.0

65.0

25.8

25.2

   

Total

100

100

100

100

   

Maternal age:

       

14-24

37.3

38.5

37.1

34.8

11.8(2)

4.0 (2)

10.2(2)

25-34

55.0

55.3

54.9

57.6

0.003

0.14

0.006

35-49

7.7

6.2

8.0

7.6

   

Total

100

100

100

100

   

Social class:

       

I + II

30.2

29.7

30.2

35.9

48.6(2)

7.4(2)

41.5(2)

III

48.2

48.1

48.2

45.5

<0.0001

0.025

0.0001

IV + V

21.6

22.2

21.6

18.6

   

Total

100

100

100

100

   

Marital status:

       

Married

88.0

79.4

89.4

90.4

25.3(1)

74.0(1)

4.3(1)

Not married

12.0

20.6

10.6

9.6

<0.0001

0.0001

0.04

Total

100

100

100

100

   

Parity of mother:

       

0

40.5

35.5

41.2

42.0

14.0(4)

24.2(4)

4.65(4)

1

35.4

35.3

35.3

35.9

0.007

<0.0001

0.33

2

15.3

16.8

15.1

14.5

   

3

5.9

8.6

5.5

4.9

   

4+

2.9

3.6

2.9

2.7

   

Total

100

100

100

100

   

Maternal smoking:

       

No

71.7

63.3

73.4

76.5

34.9(1)

46.0(1)

11.7(1)

Yes

28.3

36.7

26.6

23.5

0.0001

0.0001

0.0006

Total

100

100

100

100

   

Gestational age (wks):

       

24-37

12.8

18.0

12.1

10.1

43.2(3)

33.2 (2)

13.3(2)

38-41

77.4

70.7

78.3

80.4

0.0001

0.0001

0.001

42-47

9.8

11.3

9.6

9.5

   

Total

100

100

100

100

   

Birth weight:

       

1000-2999

27.1

32.0

26.3

23.6

27.4(2)

22.5 (2)

16.1(2)

3000-3999

64.4

61.8

64.8

67.9

0.0001

0.0001

0.0003

4000-5499

8.5

6.2

8.9

8.5

   

Total

100

100

100

100

   

Caesarean delivery:

       

No

91.0

89.8

91.2

92.6

14.1(1)

5.7(1)

9.7(1)

Yes

9.0

10.2

8.8

7.4

0.0002

0.02

0.002

Total

100

100

100

100

   

Forceps delivery:

       

No

88.2

93.4

87.4

86.9

5.9(1)

18.5(1)

1.0(1)

Yes

11.8

6.6

12.6

13.1

0.01

0.0001

0.33

Total

100

100

100

100

   

Apgar 1:

       

1-5

8.4

9.3

8.2

9.5

9.4(2)

2.1(2)

8.5(2)

6-8

30.3

31.3

30.2

28.48

0.01

0.35

0.01

9-10

96.1

59.4

61.6

62.5

   

Total

100

100

100

100

   

Number of babies in birth delivery:

       

Singleton

98.1

97.6

98.2

97.8

1.7(1)

0.2(1)

2.9(1)

Multiple birth

1.9

2.4

1.8

2.2

0.19

0.68

0.09

Total

100

100

100

100

   

Sex of baby:

       

Female

32.4

30.1

38.5

48.8

205.9(1)

74.6(1)

145.5

Male

67.4

69.9

61.5

51.2

<0.0001

0.0001

0.0001

Total

100

100

100

100

   

Breastfed or not:

       

Not breastfed

32.6

41.6

30.9

30.2

8.1(1)

29.7(1)

0.6(1)

Breastfed

67.4

58.4

69.1

69.8

0.004

0.0001

0.46

Total

100

100

100

100

   
  1. Missing values: maternal asthma none missing; year of birth none; mother's age 7 (0.2% of cases; social class 869 (27.6%*); marital status 8 (0.2%); parity 2 (0.05%); maternal smoking 1278 (31.8%*); gestational age 558 (13.9%); birth weight 114 (2.8%); caesarean section 114 (2.8%); forceps 114 (2.8%); Apgar 1 1164 (29.0%*); number of babies none missing; sex none; breastfeeding 961 (23.9%*). * = data item not collected in the first five years covered by the study. Numbers on which the percentages are based are given in additional files (see Additional file 1).