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Table 1 The distribution of various child, maternal, socio-economic, and lifestyle characteristics of interest in the total study sample and by lifetime average blood lead levels from 6 to 48 months of age, and asthma diagnosis (n = 222)

From: Early life blood lead levels and asthma diagnosis at age 4–6 years

Characteristics

Study sample

n= 222

n (%)

Lifetime average blood lead levels

(μg/dL)

Asthma

diagnosis

n= 52

n (%)

< 5

n= 70

n (%)

5–9.9

n= 99

n (%)

≥ 10

n= 53

n (%)

Child sex

 Male

113 (51)

30 (43)

47 (47)

36 (68)

34 (65)

 Female

109 (49)

40 (57)

52 (53)

17 (32)

18 (35)

Birthweight (grams)

 < 2500

15 (7)

6 (9)

7 (7)

2 (4)

3 (6)

 2500–4000 (normal)

195 (88)

57 (81)

89 (90)

49 (92)

46 (88)

 ≥ 4000

12 (5)

7 (10)

3 (3)

2 (4)

3 (6)

 Median

3270

3326

3203

3270

3326

  (IQR)

(2891–3570)

(2850–3620)

(2850–3620)

(2976–3570)

(2990–3662)

Maternal race

 White

59 (27)

33 (47)

21 (21)

5 (9)

12 (23)

 Non-white

163 (73)

37 (53)

78 (79)

48 (91)

40 (77)

Maternal age at birth (years)

 <20

68 (31)

19 (27)

33 (33)

16 (30)

13 (25)

 20-24

45 (20)

12 (17)

21 (21)

12 (23)

14 (27)

 25–30

61 (27)

21 (30)

23 (23)

17 (32)

16 (31)

 ≥ 30

48 (22)

18 (26)

22 (22)

8 (15)

9 (17)

 Median (IQR)

24.6 (19.1–29.3)

26.1 (19.6–30.7)

23.6 (19.3–29.8)

23.9 (18.4–27.5)

24.2 (20.2–29.0)

Maternal education

 Less than high school

61 (27)

12 (17)

28 (28)

21 (40)

16 (31)

 High school/GED

77 (35)

24 (34)

33 (33)

20 (38)

20 (38)

 More than high school

84 (38)

34 (49)

38 (38)

12 (22)

16 (31)

Maternal parity at 72 months of age

     

 0

79 (36)

33 (47)

33 (33)

13 (25)

18 (35)

 1

56 (25)

17 (24)

25 (25)

14 (26)

13 (25)

 2

40 (18)

10 (14)

20 (20)

10 (19)

6 (12)

 3

30 (14)

9 (13)

13 (13)

8 (15)

8(15)

 ≥ 4

17 (8)

1 (2)

8 (8)

8 (15)

7 (13)

Annual household income at 72 months of age

 < 24,999

155 (70)

34 (49)

74 (76)

47 (90)

41 (79)

 ≥ 25,000

65 (30)

36 (51)

24 (24)

5 (10)

11 (21)

Household smoking exposure at 72 months of age

 No

116 (52)

45 (64)

45 (45)

26 (49)

25 (48)

 Yes

106 (48)

25 (36)

54 (55)

27 (51)

27 (52)

Child ever breastfed by 6 months of age

 No

184 (83)

55 (79)

82 (83)

47 (89)

49 (94)

 Yes

38 (17)

15 (21)

17 (17)

6 (11)

3 (6)

Daycare attendance at 72 months of age

 No

140 (63)

47 (67)

57 (58)

36 (68)

34 (65)

 Yes

82 (37)

23 (33)

42 (42)

17 (32)

18 (35)