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Table 8 Birth order distributions and odds ratios for breast cancer among white and African-American women by race

From: Birthweight, parental age, birth order and breast cancer risk in African-American and white women: a population-based case–control study

 

Minimally adjusted ORa

Fully adjusted ORb

 

African-American

White

African-American

White

 

Case

Control

OR

95% CI

Case

Control

OR

95% CI

Case

Control

OR

95% CI

Case

Control

OR

95% CI

Full CBCSc

n = 331

n = 329

  

n = 523

n = 456

  

n = 331

n = 329

  

n = 523

n = 456

  

   1st born (ref.)

106

103

Ref.

 

191

165

Ref.

 

106

103

Ref.

 

191

165

Ref.

 

   2nd–4th born

142

151

0.8

0.6–1.2

264

226

1.0

0.7–1.3

142

151

0.8

0.6–1.2

264

226

1.0

0.7–1.3

   ≥5th born

83

75

1.0

0.7–1.5

68

65

1.0

0.7–1.5

83

75

1.0

0.7–1.5

68

65

1.0

0.7–1.5

   Mean ± SD

3.6 ± 2.7

3.3 ± 2.7

  

2.6 ± 1.9

2.6 ± 2.0

          

   Median

2.0

3.3

  

2.0

2.0

          

   Range

1–14

1–14

  

1–12

1–11

          

Born ≥1948d,e

n = 129

n = 134

  

n = 233

n = 181

  

n = 101

n = 109

  

n = 164

n = 115

  

   1st born (ref.)

37

41

Ref.

 

80

67

Ref.

 

29

31

Ref.

 

55

45

Ref.

 

   2nd–4th born

56

61

1.0

0.5–1.7

138

97

1.2

0.8–1.9

46

50

0.7

0.4–1.5

98

59

1.0

0.6–1.8

   ≥5th born

36

32

1.2

0.6–2.3

15

17

0.7

0.3–1.6

26

28

0.7

0.3–1.6

11

11

0.5

0.2–1.5

   Mean ± SD

3.6 ± 2.7)

3.3 ± 2.6)

  

2.3 ± 1.5)

2.3 ± 1.6)

          

   Median

3.0

2.5

  

2.0

2.0

          

   Range

1–14

1–14

  

1–10

1–11

          
  1. 1Adjusted for age and sampling fractions. 2Adjusted for age, sampling fractions, and other covariates as specified. 3Additional covariates for fully adjusted OR: none. 4Additional covariates for fully adjusted OR: adult body mass index >25 kg/m2, household income ≥$30,000 and maternal age. 5Restricted to participants born on or after 1 January 1948. CBCS, Carolina Breast Cancer Study; CI, confidence interval; OR, odds ratio.