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Table 1 Principal characteristics of selected meta-analyses and the adjustment performed according to the "trim and fill method"

From: Assessment of funnel plot asymmetry and publication bias in reproductive health meta-analyses: an analytic survey

Meta-analysis

Number of trials

Estimated number of missing studies

Model of Effect used

Original combined effect estimates

Adjusted effect estimates

Year of last trial included

Hofmeyr 18

12

0

Fixed

0.35 (0.22–0.56)

Unchanged

1999

Smaill 19

83

18

Random

0.39 (0.35–0.43)

0.42 (0.37–0.47)

2001

Hopkins 14

14

7

Fixed

0.92 (0.70–1.23)

0.57 (0.45–0.73)*

1993

Hopkins 20

11

3

Fixed

1.08 (0.74–1.58)

0.96 (0.68–1.36)

1996

Smaill 21

13

0

Fixed

0.24 (0.19–0.32)

Unchanged

1987

Kenyon 22

13

1

Fixed

0.90 (0.74–1.10)

0.91 (0.74–1.11)

2001

McDonald 23

13

2

Fixed

0.87 (0.74–1.02)

0.92 (0.78–1.07)

2003

Abalos 24

22

1

Fixed

0.75 (0.47–1.19)

0.73 (0.46–1.15)

1995

Knight 25

37

14

Fixed

0.87 (0.80–0.94)

0.91 (0.84–0.99)

1999

King 26

11

1

Fixed

1.49 (0.67–3.34)

1.35 (0.62–2.95)

2002

Atallah 27

11

5

Random

0.35 (0.20–0.60)

0.50 (0.32–0.78)

2001

Martin-Hirsch 13

11

3

Fixed

0.28 (0.25–0.31)

0.27 (0.25–0.30)

1994

Thacker 28

10

5

Fixed

1.39 (1.21–1.59)

1.17 (1.04–1.33)

1993

Hodnett 15

15

5

Fixed

0.91 (0.83–0.99)

0.94 (0.86–1.03)*

2002

Cheng 16

10

1

Fixed

0.63 (0.44–0.92)

0.70 (0.49–1.00)*

2002

Crowley 29

19

3

Fixed

0.20 (0.06–0.70)

0.25 (0.08–0.73)

1992

Oates-Whitehead 30

14

0

Fixed

1.05 (0.83–1.34)

Unchanged

2002

Hodnett 31

13

2

Fixed

0.99 (0.90–1.09)

0.98 (0.89–1.08)

2001

Carroli 32

10

2

Fixed

0.81 (0.70–0.93)

0.83 (0.72–0.95)

1998

Johanson 33

12

2

Fixed

0.59 (0.51–0.68)

0.60 (0.52–0.69)

1996

Hofmeyr 34

25

7

Random

0.65 (0.58–0.73)

0.72 (0.64–0.81)

2003

  1. * Conclusion is possibly affected by publication bias