Table 1 Summary of relative risks and prevalence (%) of exposure to modifiable reproductive factors in Korean women and data source

Breast cancer

 Pregnancy/age at first birth

Nulliparous

1.06 (0.82-1.36)

Case–control study

SeBCS

3

KNHANES, 2005

≤23 years

1.00

36

24 – 30 year

1.13 (0.98-1.32)

57

≥31 year

1.27 (0.98-1.66)

4

 Total period of breast feeding

Never

1.03 (0.87-1.21)

Case–control study

SeBCS

17 (18^b)

KNHANES, 2005

≤6 months

1.28 (1.07-1.53)

9 (10^b)

≥7 months

1.00

70 (72^b)

 Oral contraceptive use

Never

1.00

Meta-anlaysis

SeBCS and [31]

82

KNHANES, 2005

Ever

1.31 (1.04-1.64)

18

 Hormone replacement therapy use

Never

1.00

30 (95^c)

KNHANES, 2005

Ever

1.16 (0.36-3.78)

Meta-anlaysis

SeBCS and [31]

2 (5^c)

Ovarian cancer

 Pregnancy

Nulliparous

1.42 (1.31-1.54)

Meta-anlaysis

Ko-EVE, [32–34, 36, 37, 40–42]

3

KNHANES, 2005

Parous

1.00

97

 Breast feeding experience

Never

1.17 (1.02-1.33)

Meta-anlaysis

Ko-EVE, [36, 39, 42, 43]

17 (18^b)

KNHANES, 2005

Ever

1.00

79(82^b)

 Tubal ligation

No

1.44 (1.33-1.56)

Meta-anlaysis

Ko-EVE and [44]

75 (77^b)

Ko-EVE^d, 2009-2011

Yes

1.00

22 (23^b)

 Oral contraceptive use

Never

1.87 (0.89-3.94)

Meta-anlaysis

Ko-EVE and [45]

82

KNHANES, 2005

Ever

1.00

18