Table 3 Risk factor for retinopathy of prematurity in Iran

Variables

Studies(N^a)

OR (95%CI^b)

P-Value

Model in Meta-analysis

Twin birth

4

804

1868

46.97

0.129

1.62 (0.94 to 2.81)

0.081

Random^c

Mechanical ventilation

6

1131

2493

73.35

0.002

1.81 (0.80 to 1.73)

0.39

Random

Continuous positive pressure ventilation

2

62

131

64.11

0.095

3.97 (1.21 to 13.01)

0.023

Random

Blood transfusion (N)

16

1820

4167

91.34

< 0.001

2.38 (1.43 to 3.94)

0.001

Random

Septicemia

11

1327

2965

80.75

< 0.001

1.96 (1.10 to 3.48)

0.021

Random

Birth weight < 1000 g

9

573

2093

59.65

0.011

4.16 (2.35 to 7.35)

< 0.001

Random

Birth weight < 1500 g

10

559

1984

43.34

0.069

3.74 (2.54 to 5.49)

< 0.001

Random

Phototherapy (N)

11

1380

3355

80.69

< 0.001

1.50 (1.00 to 2.27)

0.049

Random

Oxygen therapy (N)

14

726

3124

87.39

< 0.001

3.06 (1.29 to 7.27)

0.011

Random

Need for resuscitation

2

56

212

86.50

0.006

5.01 (0.18 to 135.71)

0.338

Random

Apnea

3

114

492

72.08

0.028

4.41 (1.70 to 11.40)

0.002

Random

Congenital heart disease

2

50

246

67.29

0.08

2.13 (0.10 to 45.62)

0.626

Random

Inter-ventricular hemorrhage

11

1223

3178

76.36

< 0.001

2.24 (1.2 to 3.95)

0.005

Random

Acidosis

3

132

296

62.62

0.069

2.56 (0.81 to 8.06)

0.106

Random

Cesarean section

4

375

830

47.88

0.124

1.08 (0.53 to 2.18)

0.82

Random

Preeclampsia

2

108

237

0

0.82

0.12 (0.02 to 0.65)

0.014

Fixed^d

Respiratory distress syndrome

11

2039

2618

80.13

< 0.001

1.64 (1.03 to 2.61)

0.036

Random

Saturation above 50%

4

118

656

30.30

0.23

8.35 (3.14 to 22.18)

< 0.001

Random

Normal Vaginal Delivery

4

375

830

46.63

0.132

1.01 (0.50 to 2.02)

0.969

Random

Multiple pregnancy

6

1199

2518

40.20

0.137

0.92 (0.73 to 1.16)

0.517

Random

Gestational age ≤ 28

6

551

1440

75.88

< 0.001

5.20 (2.31 to 11.73)

< 0.001

Random

Gestational age ≤ 32

9

689

1885

64.84

0.004

7.88 (4.62 to 13.46)

< 0.001

Random

Birth weight (gr)

7

1495

2893

97.30

< 0.001

0.98 (0.97 to 0.99)

< 0.001

Random

Gestational age (week)

7

1495

2893

84.20

< 0.001

0.67 (0.59 to 0.770)

< 0.001

Random

Variables

Studies(N^a)

Mean Difference (95% CI^b)

P-Value

Case

Control

I²

P-Value

Gestational age (weeks)

18

1835

4126

94.53

< 0.001

2.08(1.50 to 2.66)

< 0.001

Random

Birth weight (gr)

19

1782

4519

95.94

< 0.001

305.39(236.09 to 374.69)

< 0.001

Random

Oxygen therapy (day)

11

1399

3214

96.04

< 0.001

−4.36(−6.09 to −2.63)

< 0.001

Random

Phototherapy (days)

4

78

308

83.80

< 0.001

−2.08(−3.81 to −0.35)

< 0.001

Random

Apgar score in the first minute

3

174

216

63.30

0.66

1.07(0.45 to 1.68)

0.001

Random

Apgar score

3

64

272

76.34

0.015

0.43(−0.25 to −1.13)

0.21

Random

Mechanical ventilation (days)

2

114

154

88.81

0.003

−4.53(−9.17 to 0.10)

0.55

Random

Bilirubin (mg/di)

3

54

186

7.70

0.33

−0.27(−1.40 to 0.86)

0.63

Random

Blood transfusion (duration)

2

98

151

0

0.98

−0.69(−0.96 to − 0.42)

< 0.001

Fixed

clinical risk index for babies

2

161

250

58.84

0.11

−0.62(− 1.40 to 0.16)

0.11

Random