Table 3

Subgroup analysis of the association between previous cesarean section and placenta previa by study characteristics

Not including current study

Including current study


Number of Studies

Random Effects Pooled OR

Lower 95% CI

Upper 95% CI

I2

Number of Studies

Random Effects Pooled OR

Lower 95% CI

Upper 95% CI

I2


Overall

37

2.199

1.964

2.462

86.1%

38

2.155

1.941

2.395

86.0%

Study design

Cohort studies

23

2.345

2.045

2.690

89.7%

24

2.284

2.014

2.591

89.5%

Case-control studies

14

1.933

1.517

2.464

71.0%

14

1.933

1.517

2.464

71.0%

Setting

Population-based studies

11

1.674

1.549

1.809

86.7%

12

1.664

1.553

1.785

56.0%

Hospital-based studies

26

2.677

2.146

3.339

86.8%

26

2.677

2.146

3.339

86.8%

Timing of PP diagnosis

Confirmed at CS

13

2.515

1.751

3.613

88.2%

13

2.515

1.751

3.613

88.2%

Other

24

1.982

1.781

2.206

80.9%

25

1.936

1.756

2.135

80.7%

Inclusion criteria

Studies analyzing 2nd births only

7

1.504

1.383

1.635

0%

8

1.540

1.442

1.645

0%

Other

30

2.462

2.138

2.835

87.6%

30

2.462

2.138

2.835

87.6%

Risk-adjustment

Adjusted for age and parity

14

1.648

1.515

1.792

52.3%

15

1.642

1.524

1.769

54.1%

Unadjusted estimates

23

2.712

2.174

3.383

87.7%

23

2.712

2.174

3.383

87.7%


Gurol-Urganci et al. BMC Pregnancy and Childbirth 2011 11:95   doi:10.1186/1471-2393-11-95

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