From: Maternal breast cancer risk in relation to birthweight and gestation of her offspring
 | Premenopausalb | Postmenopausalb | Breast cancer overall | ||||||
---|---|---|---|---|---|---|---|---|---|
No. of cases | HRc | 95% CI | No. of cases | HRc | 95% CI | No. of cases | HRc | 95% CI | |
Birthweight (g) | |||||||||
  < 2000 | 4 | 1.25 | 0.46–3.37 | 6 | 0.72 | 0.32–1.61 | 10 | 0.87 | 0.47–1.63 |
 2000–2499 | 11 | 1.10 | 0.60–2.03 | 28 | 0.84 | 0.57–1.23 | 39 | 0.90 | 0.65–1.24 |
 2500–2999 | 29 | 0.62 | 0.42–0.92d | 147 | 0.99 | 0.82–1.19 | 176 | 0.90 | 0.76–1.07 |
 3000–3499 | 158 | 1.00 |  | 470 | 1.00 |  | 628 | 1.00 |  |
 3500–3999 | 155 | 0.95 | 0.76–1.19 | 415 | 0.96 | 0.84–1.09 | 570 | 0.96 | 0.85–1.07 |
 4000–4499 | 60 | 1.06 | 0.78–1.42 | 137 | 0.99 | 0.81–1.19 | 197 | 1.01 | 0.86–1.18 |
  ≥ 4500 | 12 | 0.94 | 0.52–1.70 | 42 | 1.33 | 0.97–1.83 | 54 | 1.22 | 0.92–1.61 |
 Not known | 18 | 1.09 | 0.63–1.89 | 43 | 1.05 | 0.76–1.43 | 57 | 1.05 | 0.80–1.38 |
 p trende |  | 0.18 |  |  | 0.36 |  |  | 0.15 |  |
p interaction (trend) = 0.49 | |||||||||
Gestation (weeks) | |||||||||
 26–31 | 2 | 0.73 | 0.18–2.94 | 10 | 1.08 | 0.58–2.02 | 12 | 1.00 | 0.56–1.77 |
 32–36 | 27 | 1.22 | 0.82–1.83 | 112 | 1.03 | 0.84–1.27 | 139 | 1.06 | 0.89–1.28 |
 37–39 | 131 | 0.99 | 0.79–1.24 | 340 | 0.98 | 0.85–1.12 | 471 | 0.98 | 0.87–1.10 |
 40–41 | 195 | 1.00 |  | 521 | 1.00 |  | 716 | 1.00 |  |
  ≥ 42 | 64 | 1.23 | 0.93–1.64 | 113 | 0.94 | 0.77–1.15 | 177 | 1.03 | 0.87–1.21 |
 Not known | 24 | 0.93 | 0.60–1.42 | 192 | 1.04 | 0.88–1.23 | 216 | 1.03 | 0.88–1.20 |
 p trende |  | 0.99 |  |  | 0.52 |  |  | 0.59 |  |
p interaction (trend) = 0.74 |