Characteristics

Age group 22 - 34 years

Age group 35 - 44 years

Age group 45 years and over

Overall series

Control patients

n = 64 (%)

Breast cancer patients

n = 60 (%)

p

Control patients

n = 112 (%)

Breast cancer patients

n = 108 (%)

p

Control patients

n = 224 (%)

Breast cancer patients

n = 232 (%)

p

Control patients

n = 400 (%)

Breast cancer patients

n = 400 (%)

p

Age at first full term pregnancy

No

28 (43.8)

45 (75)

0.001

13 (11.6)

30 (27.8)

<0.001

14 (6.3)

28 (12.1)

<0.001

55 (13.8)

103 (25.8)

<0.001

<30 years

35 (54.7)

13 (21.7)

88 (78.6)

44 (40.7)

146 (65.2)

76 (32.8)

269 (67.3)

133 (33.3)

≥30 years

1 (1.6)

2 (3.3)

11 (9.8)

34 (31.5)

64 (28.6)

128 (55.2)

76 (19)

164 (41)

Number of birth

Nulliparous

28 (43.8)

45 (75)

<0.001

12 (10.7)

29 (26.9)

0.002

13 (5.8)

28 (12.1)

<0.001

53 (13.3)

102 (25.5)

<0.001

1 to 2

23 (35.9)

3 (5)

10 (8.9)

15 (13.9)

0 (0)

28 (12.1)

33 (8.3)

46 (11.5)

≥3

13 (20.3)

12 (20)

90 (80.4)

64 (59.3)

211 (94.2)

176 (75.9)

314 (78.5)

252 (63)

Duration of breastfeeding

Never

27 (42.2)

46 (75)

0.001

12 (10.7)

32 (29.6)

0.002

13 (5.8)

30 (12.9)

0.001

52 (13)

107 (26.8)

<0.001

<6 month

20 (31.3)

3 (5)

15 (13.4)

14 (13)

11 (4.9)

27 (11.6)

46 (11.5)

44 (11)

≥6 month

17 (26.6)

12 (20)

85 (75.9)

62 (57.4)

200 (89.3)

175 (76.4)

302 (75.5)

249 (62.3)