Table 4 Odds ratio, publication bias, heterogenicity, and sensitivity analysis of breast cancer risk factors

Modifiable risk factors

 Occupation (ref = housewife)

  Employee

1.18–1.49

 Education (ref = university)

  Illiterate

0.84–1.32

  Lower than diploma

0.90–1.14

 Marital status (ref = married)

  Single, divorced, widow

1.09–1.34

 Place of residence (ref = rural)

  Urban

1.13–1.69

 Age of marriage(ref =  < 18)

  18–24

1.22–1.23

  25–29

1.87–2.28

   > 29

1.23–3.48

 BMI (ref = normal)

  Underweight (< 18.5)

0.56–1.05

  Overweight (25–29.9)

1.11–1.39

  Obese (≥ 30)

1.56–2.37

 Physical activity (ref = regular, active)

  moderate, occasionally

1.12–1.51

  Never, seldom

1.31–2.02

 Smoking (ref = no)

  Yes

1.75- 1.88

 Second-hand smoking (ref = no)

  Yes

1.83–1.90

 Alcohol use (ref = no)

  Yes

0.40–2.01

 supplement intake (ref = no)

  Yes

0.46–0.73

 Parity (ref = nulliparous)

  Yes

0.88–1.06

 Abortion history (ref = no)

  Yes

1.21–1.63

 OCP use (ref = no)

  Yes

1.26–1.41

 HRT (ref = no)

  Yes

0.83–1.31

 Breastfeeding history (ref = no)

  Yes

0.88-.0.93

 Breastfeeding duration (ref =  ≥ 24 months)

   < 24 months

1.09–2.14

 Non-modifiable risk factors

  Age of menarche (ref =  ≥ 14)

  12–13

1.48–1.74

   < 12

1.71–4.33

 Age of menopause (ref =  ≥ 49)

     < 49

1.27–3.29

 Menopause status (ref = no)

  Yes

1.10–1.30

 Family history of breast cancer (ref = no)

  Yes

2.28–2.65

 Family history of cancer (ref = no)

  Yes

1.45–3.58

 History of radiation exposure (ref = no)

  Yes

3.46–3.49