Table 3 Results of the pooled OR, heterogeneity and publication bias detection

Before childbirth

 Elder

P = 0.79, I² = 0%^a

1.20 (0.99, 1.45)^b

7

-

-

-

 Gestational hypertension

P < 0.01, I² = 90%

2.14 (1.77, 2.58)

8

399

6.67

< 0.01

 GDM

P < 0.01, I² = 84%

1.82 (1.52, 2.17)

8

253

4.96

< 0.01

 Primipara

P = 0.62, I² = 0%^a

0.81 (0.67, 0.97)

6

4

2.26

0.07

 Multiple pregnancy

P = 0.12, I² = 48%^a

1.44 (0.91, 2.25)^b

4

-

-

-

 Genital tract inflammation

P = 0.15, I² = 43%^a

2.51 (2.09, 3.02)

9

275

-2.68

0.14

 AP

P = 0.14, I² = 43%^a

2.28 (2.01, 2.59)

15

808

0.49

0.63

During childbirth

 Premature delivery

P = 0.20, I² = 32%^a

1.21 (0.93, 1.57)^b

6

-

-

-

 Caesarean section

P < 0.01, I² = 77%

2.03 (1.80, 2.29)

19

580

0.79

0.61

 Operative vaginal delivery

P = 0.15, I² = 44%^a

1.23 (0.94, 1.62)^b

4

-

-

-

 Episiotomy

P = 0.41, I² = 0%^a

2.64 (1.76, 3.94)

4

35

2.19

0.09

 PROM

P < 0.01, I² = 86%

2.54 (2.23, 2.89)

19

1165

5.31

0.01

 Prolonged labor

P = 0.12, I² = 48%^a

1.32 (1.10, 1.57)

8

41

-2.00

0.44

After childbirth

 Placenta remnant

P = 0.25, I² = 23%^a

2.59 (1.94, 3.48)

7

118

2.05

0.23

 Postpartum hemorrhage

P = 0.65, I² = 0%^a

2.43 (2.13, 2.77)

18

1151

1.30

0.05