Table 4 Associations between reproductive factors with risk of non-serous epithelial ovarian cancer (endometrioid, clear cell, mucinous and other epithelial histologies) in the Asia Cohort Consortium.

From: Reproductive factors and risk of epithelial ovarian cancer: results from the Asia Cohort Consortium

Variable

Value

Total

Cases

Model HRa

Parous

No

20,592

30

1.00 (Ref)

 

Yes

293,859

218

0.53 (0.35–0.78)

Number of children

0

11,793

17

1.00 (Ref)

 

1-2

142,680

123

0.65 (0.39–1.09)

 

3-4

96,500

54

0.48 (0.28–0.83)

 

5+

32,622

17

0.46 (0.23–0.92)

 

P-trendb (incl 0)

  

0.02

 

P-trendb (parous only)

  

0.22

Age at first deliveryc

≤20 y

28,819

18

1.00 (Ref)

 

21–25 y

130,681

88

1.00 (0.59–1.71)

 

26–30 y

87,662

69

0.94 (0.53–1.66)

 

31+ y

19,135

18

0.98 (0.48–1.97)

 

P–trendb

  

0.98

Breastfeeding (parous women only)d

Never

15,829

13

1.00 (Ref)

 

Ever

103,219

72

1.19 (0.65–2.18)

Age at menarche

<13 y

22,306

29

1.00 (Ref)

 

13-14 y

107,121

93

0.79 (0.52–1.20)

 

15-16 y

110,035

92

0.90 (0.59–1.39)

 

17+ y

56,863

22

0.54 (0.30–0.97)

 

P–trendb

  

0.10

Age at menopausee

<45 y

29,757

8

1.00 (Ref)

 

45–49 y

66,478

35

1.87 (0.83–4.24)

 

50–54 y

82,031

47

2.03 (0.90–4.58)

 

55+ yrs

10,222

11

4.65 (1.75–12.37)

 

P-trendb

  

0.01

OC usef

No use

155,388

129

1.00 (Ref)

 

Ever use

35,110

27

0.88 (0.57–1.36)

MHT useg

No use

104,168

63

1.00 (Ref)

 

Ever use

9623

4

0.84 (0.30–2.39)

BMI

<18.5 kg/m2

16,672

11

0.83 (0.45–1.56)

 

18.5–22.9 kg/m2

136,021

107

1.00 (Ref)

 

23–24.9 kg/m2

78,267

56

0.92 (0.67–1.28)

 

25–29.9 kg/m2

79,182

63

1.17 (0.85–1.61)

 

30+ kg/m2

11,335

13

1.69 (0.94–3.02)

 

Per 5 kg/m2 increase

  

1.20 (1.00–1.44)

 

P-trendb

  

0.05

Height

≤149.9 cm

74,398

51

1.00 (Ref)

 

>149.9–153.0 cm

86,511

52

0.69 (0.46–1.02)

 

>153.0–157.9 cm

77,005

62

0.84 (0.57–1.24)

 

>157.9 cm

83,838

85

1.02 (0.69–1.51)

 

Per 5 cm increase

  

1.05 (0.94–1.18)

 

P-trendb

  

0.41

Smoking

Never smoked

281,845

228

1.00 (Ref)

 

Ever smoked

23,360

18

0.96 (0.59–1.56)

  1. aModels were stratified by the cohort and age at enrollment (5-year age groups: <40, 40–44, to 70–74, 75+ years) and were adjusted for parity (number of children; 0 [ref], 1-2, 3-4, >4, missing).
  2. bP-trend is the P-value for the test of linear trend using continuous variables.
  3. cAge at first delivery was restricted to parous women who had data on number of deliveries and these models were adjusted for number of deliveries as follows (1-2 [ref], 3-4, >4). LSS was not included due to missing data on number of deliveries.
  4. dData on breastfeeding were only available in JPHC1, JPHC2, Miyagi, Ohsaki, KMCC, KNCC and Namwon.
  5. eAnalyses of age at menopause was restricted to postmenopausal women.
  6. fData on OC use were only available in Miyagi, Ohsaki, KMCC, KNCC, Namwon, SCHS and SWHS.
  7. gData on MHT use were only available in Miyagi, Ohsaki, KMCC, KNCC, Namwon, SCHS and SWHS.
  8. BMI body mass index, MHT menopausal hormone therapy, OC oral contraceptive.
  9. Bold values indicate statistically significant results.
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