Table 1 Secondary analyses in meta-analyses reporting only birthweight mean difference outcome (N = 21)

Abou El Senoun 2010 [13]

1

55

−170 (−558, 218)

0.39

1.13 (0.85, 1.51)

0.39

Alfirevic 2010 [14]

7

3,887

28 (−10, 66)

0.15

0.96 (0.89, 1.04)

0.28

Alfirevic 2010 [15]

2

5,914

−18 (−42, 7)

0.16

1.08 (0.97, 1.19)

0.15

Begley 2010 [16]

2

3,207

−77 (−109, −45)

< 0.01

1.49 (1.27, 1.77)

< 0.01

Bevilacqua 2010 [17]

7

5,372

−83 (−124, −42)

< 0.01

1.04 (1.02, 1.08)

< 0.01

Blanco 2011 [18]

2

786

113 (−45, 271)

0.16

0.74 (0.48, 1.16)

0.19

Buchanan 2010 [19]

7

692

−12 (−91, 67)

0.76

1.00 (0.97, 1.03)

0.87

Coleman 2010 [20]

3

614

158 (−53, 370)

0.14

0.65 (0.36, 1.18)

0.16

Crowther 2011 [21]

9

5,626

−76 (−118, −34)

< 0.01

1.02 (1.01,1.03)

0.01

Dhulkotia 2010 [22]

6

1,388

24 (−36, 83)

0.44

0.93 (0.77, 1.13)

0.48

Gebreselassie 2011 [23]

17

6,208

39 (−7, 85)

0.09

0.88 (0.76, 1.02)

0.08

Imdad 2011 [24]

13

4,189

60 (33, 87)

< 0.01

0.79 (0.71, 0.87)

< 0.01

Lassi 2010 [25]

2

1,050

11 (−39, 62)

0.66

0.98 (0.84, 1.14)

0.78

Mackeen 2011 [26]

2

117

159 (−44, 361)

0.13

0.97 (0.93, 1.02)

0.19

Mak 2010 [27]

4

251

8.33 (−143, 159)

0.91

0.99 (0.62, 1.58)

0.96

4/6 primary studies were accessible

Middleton 2010 [28]

2

159

−3 (−180, 175)

0.98

0.99 (0.53, 1.90)

0.99

Nabhan 2011 [29]

1

125

−100 (−364, 164)

0.46

1.18 (0.78, 1.80)

0.46

Quinlivan 2011 [30]

4

537

8.5 (−85, 102)

0.86

0.97 (0.67, 1.41)

0.88

Rumbold 2011 [31]

5

7,497

6.1 (−17, 29)

0.61

0.99 (0.91, 1.08)

0.84

Stampalija 2010 [32]

1

3,133

−34 (−69, 0.63)

0.05

1.15 (0.99, 1.33)

0.05

Vazquez 2011^a[33]

1

128

−461 (−608, −314)

< 0.01

4.91 (2.88, 8.37)

< 0.01

Data from meta-analysis where outcome was analysed as continuous for one intervention and as binary for another.