Table 4

Crude and adjusted odds ratios (OR) and 95% confidence intervals (95% CI) for postmenopausal breast cancer risk factors among parous women
Variable Events Crude OR Adjusted OR1
Case/control (95%CI) (95%CI)
Parity
 Overall 455/481
 1 – 3 130/76 1 1
 4 – 6 227/197 0.67 (0.47 – 0.94) 0.74 (0.50 – 1.09)
 7+ 98/208 0.27 (0.19 – 0.39) 0.30 (0.20 – 0.47)
 P for trend < 0.001 < 0.001
Age at first childbirth
 Overall 454/481
 <15 41/56 0.87 (0.56 – 1.34) 0.55 (0.28 – 1.10)
 15 - 24 318/381 1 1
 ≥ 25 95/44 2.57 (1.75 – 3.79) 1.24 (0.40 – 3.80)
 P for trend < 0.001 0.77
Breastfeeding (months)
 Overall 454/481
 Never 21/20 0.63 (0.33 – 1.20) 0.93 (0.29 – 1.86)
 1 – 94 268/162 1 1
 95 – 162 131/149 0.53 (0.39 – 0.72) 0.87 (0.27 – 2.78)
 > 162 34/150 0.13 (0.08 – 0.21) 0.32 (0.08 – 1.22)
 P for trend < 0.001 0.30
Breastfeeding per child
 Overall 454/479
 Never 21/20 0.91 (0.47 – 1.78) 0.98 (0.71 – 1.35)
 < 12 months 125/110 1 1
 ≥ 12 months 308/349 0.77 (0.57 – 1.04) 0.92 (0.45 – 1.88)
 P for trend 0.20 0.68
OCP usage (months)
 Overall 454/481
 Never 178/236 1 1
 1 – 48 135/90 1.50 (1.15 – 1.95) 1.99 (1.03 – 3.83)
 49 – 116 73/73 1.98 (1.42 – 2.77) 2.25 (1.12 – 4.49)
 > 116 68/82 1.32 (0.90 – 1.93) 1.40 (0.66 – 2.99)
 P for trend 0.36 0.10

1Adjusted for all variables in the table in addition to age, age at menarche, education, BMI and family history of breast cancer.

Ghiasvand et al.

Ghiasvand et al. BMC Cancer 2012 12:414   doi:10.1186/1471-2407-12-414

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