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Table 3 A mutually adjusted model of pregnancy related variables and risk of ER+PR+ vs. ER-PR- breast cancer

From: Reproductive factors and risk of hormone receptor positive and negative breast cancer: a cohort study

  Age and center stratified Multivariable adjusted1 Postmenopausal women2
  ER+PR+ ER-PR- ER+PR+ ER-PR- ER+PR+ ER-PR-
(n = 3387) (n = 944) (n = 3387) (n = 944 ) (n = 1755) (n = 477)
Reproductive factor HR 95% CI HR 95% CI HR 95% CI HR 95% CI HR 95% CI HR 95% CI
Number of full-term childbirths 3
1 child 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference
2 children 0.93 (0.84-1.03) 0.97 (0.80-1.19) 0.93 (0.84-1.03) 0.98 (0.80-1.19) 0.96 (0.83-1.10) 0.90 (0.69-1.19)
≥3 children 0.77 (0.68-0.87) 0.83 (0.66-1.05) 0.77 (0.68-0.87) 0.84 (0.66-1.06) 0.79 (0.67-0.93) 0.90 (0.65-1.22)
P for trend   <0.001   0.09   <0.001   0.10   0.002   0.54
Subtype heterogeneity4     0.53     0.47     0.22
Age at first full-term childbirth 3
≤19 years 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference
20–24 years 1.05 (0.92-1.19) 1.11 (0.88-1.40) 1.05 (0.92-1.19) 1.10 (0.87-1.39) 1.17 (0.97-1.40) 1.14 (0.82-1.59)
25–29 years 1.16 (0.99-1.35) 0.96 (0.72-1.28) 1.16 (0.99-1.36) 0.96 (0.72-1.28) 1.32 (1.05-1.64) 1.02 (0.68-1.54)
30–34 years 1.24 (1.00-1.53) 0.83 (0.55-1.25) 1.24 (1.00-1.53) 0.83 (0.55-1.25) 1.57 (1.16-2.11) 0.88 (0.49-1.57)
≥35 years 1.32 (0.96-1.82) 0.69 (0.35-1.36) 1.30 (0.95-1.79) 0.69 (0.35-1.36) 1.64 (1.05-2.56) 0.81 (0.32-2.03)
P for trend   0.02   0.19   0.02   0.19   0.002   0.51
Subtype heterogeneity4     0.03     0.03     0.05
Age at last full-term childbirth 3
Less than 25 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference
Between 25 and 30 0.90 (0.80-1.02) 1.15 (0.93-1.44) 0.90 (0.80-1.02) 1.16 (0.93-1.44) 0.87 (0.74-1.02) 1.13 (0.83-1.53)
Between 30 and 35 0.97 (0.83-1.13) 1.33 (1.00-1.77) 0.97 (0.84-1.13) 1.33 (1.00-1.77) 0.85 (0.69-1.04) 1.27 (0.86-1.86)
Greater than 35 0.89 (0.72-1.09) 1.29 (0.88-1.90) 0.89 (0.73-1.10) 1.30 (0.88-1.91) 0.83 (0.63-1.10) 1.39 (0.83-2.34)
P for trend   0.53   0.10   0.58   0.09   0.18   0.18
Subtype heterogeneity4     0.17     0.17     0.09
Time since last full-term childbirth 3
≤20 years 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference
>20 years 0.87 (0.77-0.98) 1.01 (0.81-1.26) 0.86 (0.77-0.97) 1.00 (0.80-1.25) 0.90 (0.73-1.12) 1.10 (0.74-1.65)
P for significance   0.02   0.94   0.02   0.99   0.35   0.63
Subtype heterogeneity4     0.24     0.24     0.29
  1. 1Stratified by age at recruitment and center and further adjusted for BMI, height, menopausal status at enrolment, HRT use, physical activity, smoking status, alcohol consumption and attained level of education; 2stratified by age at recruitment and center and further adjusted for BMI, height, HRT use, physical activity, smoking status, alcohol consumption and attained level of education; 3mutually adjusted for the pregnancy related variables in this table; 4heterogeneity between ER+PR+ and ER-PR- tumors was assessed on the trend score using the data augmentation method as described by Lunn and McNeil.