Table 1 Characteristics of the primary studies included in the meta-analysis

Castellsague X ¹⁴

Case control

USA

20 to 54 years

High

671

383

2963

OR

0.58

0.43

0.78

0.87

0.63

1.2

Age and Parity

Lacey JV Jr. ¹⁶

Case control

USA

20 to 74 years

High

87

357

614

OR

0.9

0.6

1.4

1.4

0.8

2.3

Age, parity, and OC usage

Kjaer SK ¹⁷

Cohort

Denmark

Women who had a tubal sterilization (1977–1993)

High

65,232

–

–

SIR

0.7

0.5

1

–

–

–

–

Rosenblatt KA ¹⁵

Case control

Seven countries

Older than 15

Moderate

377

101

1077

OR

–

–

–

1.26

0.79

2

Parity and age, hospital and date of diagnosis

Wernli KJ ¹¹

Cohort

China

Women employed in the textile industry

Moderate

–

147

–

HR

–

–

–

1.1

0.79

1.56

Age at baseline and reproductive category

Nagle CM ⁶

Case control

Australia

Cancer registries

Moderate

425

404

1225

OR

–

–

–

0.4

0.3

0.7

Age, education, parity and hormone contraceptive use

Iversen L ¹⁸

Cohort

United Kingdom

Women who were using oral contraceptives

High

2801

4

2801

–

–

–

–

–

–

–

–

Gaitskell K ¹⁰

Cohort

United Kingdom

UK women

High

206,233

8571

767,251

RR

–

–

–

0.98

0.93

1.03

Age, region, socioeconomic status, parity, age at first birth, hysterectomy, smoking, alcohol intake, physical activity, body mass index, and use of the oral, contraceptive pill or menopausal hormones

Winer I ⁹

Cohort

USA

50 to 79 years, postmenopausal

High

14,499

945

61,984

HR

0.87

0.75

1.05

0.9

0.76

1.07

Age stratum at randomization and region

Falconer H ²

Cohort

Switzerland

Swedish women

High

80,765

35,430

5,304,421

HR

–

–

–

0.73

0.65

0.83

Age, parity, calendar time and education status