Table 2 Development scores of ELEMENT and PROGRESS children, by age and birth mode.

ELEMENT^a (BSID-II^b)

 Mental Development Index

  3 months

900

93.68

5.71

264

92.72

5.95

632

94.07

5.54

  6 months

916

96.00

6.31

263

95.63

6.01

648

96.14

6.39

  12 months

1322

96.43

9.30

359

96.18

9.53

955

96.55

9.21

  18 months

1317

89.22

9.69

350

88.93

9.26

958

89.36

9.85

  24 months

1303

88.91

12.54

356

88.29

11.95

940

89.13

12.77

  30 months

1057

90.62

9.69

296

90.66

9.32

756

90.58

9.84

  36 months

1167

90.85

9.50

321

91.26

9.49

841

90.66

9.50

 Psychomotor Development Index

  3 months

900

85.87

6.98

264

84.77

7.53

632

86.31

6.70

  6 months

915

93.07

9.78

263

92.18

9.82

647

93.43

9.75

  12 months

1321

90.74

10.07

359

90.39

9.96

954

90.89

10.12

  18 months

1312

91.56

8.91

348

91.04

9.11

955

91.74

8.84

  24 months

1303

93.72

10.56

355

93.11

10.86

941

93.94

10.44

  30 months

1056

93.05

10.93

295

93.29

10.74

756

92.96

11.01

  36 months

1162

94.57

11.48

320

94.90

11.66

837

94.42

11.38

PROGRESS^c (BSID-III^d)

 Language

  6 months

629

86.35

12.68

332

86.45

12.78

297

86.23

12.60

  12 months

558

80.34

10.80

301

79.59

10.52

257

81.22

11.07

  18 months

525

88.94

11.42

282

88.53

11.71

243

89.41

11.08

  24 months

541

89.68

9.13

277

89.12

9.71

264

90.27

8.46

 Motor

  6 months

629

93.83

12.62

332

92.56

12.94

297

95.25

12.10

  12 months

557

88.23

10.02

301

86.90

9.52

256

89.79

10.37

  18 months

523

95.35

9.74

282

94.35

9.89

241

96.51

9.46

  24 months

540

93.95

9.46

277

93.39

9.41

263

94.54

9.50

 Cognitive

  6 months

629

97.51

12.16

332

96.99

12.05

297

98.10

12.28

  12 months

558

96.10

10.12

301

95.81

9.76

257

96.44

10.54

  18 months

525

96.25

10.21

282

96.06

10.91

243

96.46

9.36

  24 months

541

92.36

8.58

277

92.11

8.68

264

92.61

8.48