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Table 5 Invasive breast cancer risk by birthweight and gestation of most-recent singleton birtha by menopausal statusb

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

  1. HR hazard ratio, CI confidence interval
  2. aWomen are censored (removed from further analytic follow-up) upon reaching a twin pregnancy
  3. bMenopausal status at breast cancer incidence
  4. cAdjusted for: attained age (Cox regression time scale); time since recruitment to cohort (0, 1–2, 3+ years); birth cohort (1908–1939, 1940–1949, 1950–1959, 1960–1969, 1970–1996); benign breast disease (yes, no); family history of breast cancer in first-degree relatives (yes, no); socio-economic score (ACORN score as trend, missing); own birthweight (trend, missing); age at menarche (trend, missing); parity (trend); age at first pregnancy (trend); cumulative duration of breast feeding (none, duration trend when reported); current oral contraceptive use before menopause (yes, no); height at age 20 (trend, missing); alcohol consumption (never regular, trend current drinker 1 to < 60 g/day, current drinker 60+ g/day, past drinker, drinker with unknown details); age started smoking (never, < 17, 17–19, 20+, missing); physical activity (log(metabolic equivalent) trend, missing); pre-menopausal body mass index at age 20 years (trend, missing); menopausal status (pre- or post-menopausal), and for those post-menopausal, post-menopausal body mass index (trend, missing), menopausal hormone therapy use (never used, ex-user, current oestrogen-only user, current oestrogen plus progestogen user, current user of other types, missing), and age at menopause (trend, missing)
  5. dp < 0.05
  6. eExcluding not known category