Table 2.
Association between paternal and maternal ages at birth and risk of breast cancer in daughters
| Age at birth of the subjects (yrs) | Cases (%) | Controls (%) | OR (95% CI)1 | OR (95% CI)2 |
| Paternal age | ||||
| Mean ± SD | 33.1 ± 7.5 | 32.5 ± 7.2 | 1.1 (1.00–1.28)† | |
| <30 | 362 (35.8) | 400 (39.6) | 1.0 | 1.0 |
| 30–34 | 266 (26.3) | 261 (25.8) | 1.2 (0.92–1.45) | 1.0 (0.79–1.34) |
| 35–39 | 169 (16.7) | 174 (17.2) | 1.1 (0.83–1.40) | 1.0 (0.71–1.39) |
| ≥40 | 214 (21.2) | 176 (17.4) | 1.4 (1.07–1.76) | 1.6 (1.04–2.32) |
| P for trend | 0.025 | 0.090 | ||
| Maternal age | ||||
| Mean ± SD | 28.7 ± 6.4 | 28.3 ± 6.5 | 1.1 (0.97–1.28)† | |
| <25 | 285 (28.2) | 330 (32.6) | 1.0 | 1.0 |
| 25–29 | 302 (29.9) | 297 (29.4) | 1.2 (0.97–1.54) | 1.2 (0.95–1.56) |
| 30–34 | 237 (23.4) | 192 (19.0) | 1.5 (1.18–1.95) | 1.4 (1.00–1.94) |
| ≥35 | 187 (18.5) | 192 (19.0) | 1.1 (0.88–1.48) | 0.8 (0.55–1.27) |
| P for trend | 0.079 | 0.998 |
1OR adjusted for family history of breast cancer in 1st or 2nd degree relatives and lifetime estrogen exposure duration
2OR adjusted for maternal age or paternal age (mutual parental age, categorical value) in addition to the variables in the model 1
†OR per 10 year