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Table 2 The distribution of women in the control group (n = 2167) and patients with breast cancer (n = 1492) according to the reproductive factors.

From: Breast cancer risk factors in Turkish women – a University Hospital based nested case control study

Factors women in the control group
(n = 2167)
patients with breast cancer
(n = 1492)
Number of children   
Nullipara 451 (20.8%) 241(16.2%)
≥ 1 1716 (79.2%) 1251 (83.8%)
≥ 4 353 (16.3%) 324 (21.7%)
1 312 (14.4%) 238 (12.4%)
2 678 (31.3%) 506 (33.9%)
3 373 (17.2%) 183 (15.8%)
Age at first birth (years)   
<25 1697 (78.3%) 1158 (77.6%)
25–29 353 (16.3%) 231 (15.5%)
30–34 99 (4.6%) 64 (4.3%)
≥ 35 18 (0.8%) 39 (2.6%)
Breast feeding   
Never 35 (1.6%) 126 (8.5%)
Ever 2132 (98.4%) 1366 (91.5%)
Spontaneous abortion   
Never 1540 (71.1%) 1156 (77.5%)
Ever 627 (28.9%) 336 (22.5%)
Induced abortion   
Never 1237 (57.1%) 750 (50.3%)
Ever 930 (42.9%) 742 (49.7%)
Oral contraceptive use   
Never 1565 (72.2%) 1217 (81.6%)
Ever 602 (27.8%) 275 (18.4%)
Hormone replacement therapy   
Never 1933 (89.2%) 1431 (95.9%)
Ever 234 (10.8%) 61 (4.1%)
Age at menopause (years)   
<50 1553 (71.7%) 971 (65.1%)
≥ 50 614 (28.3%) 521 (34.9%)