Table 1 Characteristics of women of the Jerusalem Perinatal Study cohort (1964–1976) by breast cancer status

Age at 1st birth^a

 <20

3890

9.6

104

5.0

3786

9.8

 20-25

16,472

40.6

649

31.3

15,823

41.1

 25-30

10,685

26.3

661

31.9

10,024

26.0

 30-35

5669

14.0

402

19.4

5,267

13.7

 35-40

3030

7.5

208

10.0

2822

7.3

 ≥40

840

2.1

49

2.4

791

2.1

Ethnic origin

 Israel

5372

13.2

297

14.3

5075

13.2

 West Asia

11,484

28.3

584

28.2

10,900

28.3

 North Africa

8665

21.3

334

16.1

8331

21.6

 Europe

15,065

37.1

858

41.4

14,207

36.9

Birth year

 Before 1945

20,538

50.6

1331

64.2

19,207

49.9

 1945 or later

20,048

49.4

742

35.8

19,306

50.1

Parity

 1

8794

21.7

370

17.8

8424

21.9

 2-3

18,381

45.3

1,062

51.2

17,319

45.0

 ≥4

13,374

33.0

640

30.9

12,734

33.1

 Unknown

37

0.001

1

0

36

0.1

SEP based on woman’s education

 0-8 years

10,618

26.2

489

23.6

10,129

26.3

 9-12 years

14,020

34.5

702

33.9

13,318

34.6

 >12 years

12,144

29.9

728

35.1

11,416

29.6

 Unknown

3804

9.4

154

7.4

3650

9.5

SEP based on husband’s occupation

 Low

9853

24.3

428

20.6

9425

24.5

 Middle

15,456

38.1

806

38.9

14,650

38.0

 High

15,277

37.6

839

40.5

14,438

37.5