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Table 1 Characteristics of 102,927 women from the Generations Study, recruited 2003–2013

From: Smoking and risk of breast cancer in the Generations Study cohort

Study population

No. of subjects

%

Year of birth

 1908–1939

5917

5.8

 1940–1949

21,488

20.9

 1950–1959

24,735

24.0

 1960–1969

23,749

23.1

 1970–1996

27,038

26.3

Year of recruitment

 2003–2005

33,807

32.9

 2006–2007

48,489

47.1

 2008–2013

20,631

20.0

Age at recruitment, years

 16–34

23,289

22.6

 35–44

23,116

22.5

 45–54

24,385

23.7

 55–64

23,837

23.2

 65–74

7308

7.1

 75–102

992

1.0

Age at menarche, years

 7–11

20,658

20.1

 12–14

62,291

60.5

 15–19

9353

9.1

 Not known or anomalousa

10,625

10.3

Family history of breast cancer in first-degree relatives

 No

87,030

84.6

 Yes

15,897

15.4

Smoking status, at entry into cohort

 Never smoked

66,013

64.1

 Current smoker

8491

8.3

 Former smoker

28,300

27.5

 Ever smoker, status unknown at this time

123

0.1

Alcohol consumption, at entry into cohort

 Never regular

10,574

10.3

 Current drinker (< 60 g/day)

63,690

61.9

 Current drinker (≥ 60 g/day)

1280

1.2

 Current drinker, amount unknown

4306

4.2

 Former drinker

13,513

13.1

 Ever drinker, status unknown at this time

9564

9.3

Total number of subjects

102,927

100.0

  1. Total number of subjects excludes 13 women (including 1 who developed breast cancer) with self-contradictory information for parity or smoking
  2. aIncludes 2 women reporting menarche before age 5 years, 23 at ages 20–33 years, and 23 reporting never having periods