Table 2 Associations of reproductive tract infections and estrogen exposure with breast cancer risk

Reproductive tract infections

 No

775 (77.3)

812 (73.4)

1.00 (reference)

1.00 (reference)

 Yes

228 (22.7)

295 (26.6)

0.81 (0.67, 0.99)

0.80 (0.65, 0.98)

Number of menstrual cycles

  ≤ 323

302 (30.3)

408 (37.1)

1.00 (reference)

1.00 (reference)

  > 323

694 (69.7)

691 (62.9)

1.36 (1.13, 1.63)

1.74 (1.38, 2.20)

Reproductive time—Duration of parity—Breastfeeding duration (years)

  ≤ 25

356 (35.8)

339 (30.8)

1.00 (reference)

1.00 (reference)

  > 25

639 (64.2)

760 (69.2)

0.80 (0.67, 0.96)

0.78 (0.60, 1.02)

Reproductive time—Duration of all pregnancies—Breastfeeding duration (years)

  ≤ 25

357 (35.9)

340 (30.9)

1.00 (reference)

1.00 (reference)

  > 25

638 (64.1)

759 (69.1)

0.80 (0.67, 0.96)

0.78 (0.59, 1.02)