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Table 3 Subgroup analysis of the association between previous cesarean section and placenta previa by study characteristics

From: Risk of placenta previa in second birth after first birth cesarean section: a population-based study and meta-analysis

 

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%