Table 1 Characteristic of studies selected

Newborns

 Okereke [27]

Cross-sectional

EEUU

32 (41)

46 (59)

–

–

3.2 (0. 41)^α

3.5 (0.5)^α

11.25 (3.98)

11.9 (4.4)

TOBEC

16 (13.8)

12.7 (12.8)

Serum

RIA

 Javaid⁾ [28]

Cohort

UK

50 (43)

67 (57)

–

–

3.2 (0.5)^α

3.51 (0.5)^α

15.9 (13.6;19.4)^¶

14.5 (12;16)^¶

DXA

9.1(5.9;13.9)^¶

7.4 (4.2;11.4)^¶

Serum

RIA

 Euclydes [29]

Cohort

Brazil

62 (59.6)

42 (40.4)

–

–

3.4 (0.4)^α

3.34 (0.4)^α

9.8 (4.1)

8.2 (3.6)

PG

29 (26.9)

22.8 (25.1)

Plasma

ELISA

0.25 to 0.5 years

 Estampador [30]

Cohort

Sweden

15 (48)

16 (52)

0.32 (0.03)

0.32(0.03)

6.2 (1.07)^α

6.9 (0.69)^α

25.6 (0.79)

27.1(0.25)

PG

4.9 (2.9)

4 (1.6)

Plasma

RIA

 de Fluiter [31]

Cohort

Netherland

138 (46)

159 (54)

0.25

0.25

5.7 (5.1;6.2)^α

6.2 (5.7;6.6)^α

23.3 (19.6;26.5)^¶

22.1(19.0;24.6)^¶

PG

1.7(1.5;1.9)^¶

1.3 (1.1;1.5) ^¶

Plasma

MMA

138 (46)

159 (54)

0.5

0.5

7.3 (6.8–7.8)

7.9 (7.3;8.4)

25.1 (21.6;28.9)^¶

23.5 (20.0;26.7)^¶

PG

0.9(0.6;1.1)^¶

0.8 (0.7;1.0) ^¶

Plasma

MMA

3 to 5.9 years

 Erhardt [32]

Cohort

Europe (eight countries)

47 (53)

42 (47)

3 to 3.9^❢

3;3.9^❢

16.2 (1)

16.3 (0.9)

16.8 (2.9)

15.6 (2.5)

Skinfolds

2.0 (1.5;3.8)^¶

1.5 (1.1;2.5) ^¶

Serum

ELISA

33 (50)

33 (50)

4 to 4.9^❢

4;4.9^❢

15.8 (0.8)

16 (0.8)

16.6 (2.5)

15.1 (2.3)

Skinfolds

1.9 (1.5;2.7)^¶

1.3 (1.0;1.7) ^¶

Serum

ELISA

32 (53)

28 (47)

5 to 5.9^❢

5;5.9^❢

15.6 (0.9)

15.7 (0.9)

16.5 (3.2)

14.5 (3.2)

Skinfolds

1.9 (1.5;2.7)^¶

1.2 (0.9;2.4) ^¶

Serum

ELISA

 Jáuregui [33]

Cross-sectional

Mexico

197 (49)

203 (51)

4.7 (0.5)

4.8(0.6)

0.2(1) ^†

0.2 (1.1) ^†

25 (5.7)

22.8 (5.8)

BIA

3.5 (3.1)

2.6 (2.7)

-

ELISA

 Francis [34]

Cohort

EEUU

365 (48)

396 (52)

4.8 (0.71)

4.8(069

0.05(0.9)

0.2(1.1)

19.7(6.8)

19.9(6.6)

PGA

6.7 (1.9)

3.83(1.0)

-

MMA

6 to 7.9 years

 Garnett [35]

Cohort

Australia

137 (54)

118 (46)

7.8 (0.6)

7.9(0.6)

16.9 (2.3)

16.7 (2.5)

23.6 (8.4)

17.4 (8.6)

DXA

3.4 (3.2;3.6)^❡

2.2 (2.0;2.4)^❡

Serum

RIA

 Kim (2011) [36]

Cross-sectional

Korea

229 (50)

231 (50)

7.8 (0.5)

7.9 (0.5)

15.5 (1.4)

16 (1.2)

16.7 (4.1)

13.8 (4.1)

BIA

3.4 (2.1)

2.5 (1.8)

Serum

RIA

 Metcalf [37]

Cohort

UK

158 (56)

122 (44)

6.9 (0.3)

6.9 (0.3)

16.4 (2.8)

15.7 (2.1)

21.9 (12.8) ^ℑ

14.4 (8.0) ^ℑ

DXA

4 (5.2) ^ℑ

2.6 (2.7) ^ℑ

Serum

RIA

148 (55)

121 (45)

7.8(0.3)

7.9 (0.3)

16.9 (3.1)

15.9 (2.3)

23.3 (14.5) ^ℑ

14.8 (9.8) ^ℑ

DXA

4.4 (6.6) ^ℑ

2.6 (3.1) ^ℑ

Serum

RIA

 Jeffery [38]

Cohort

UK

101

134

7.0

7.0

0.54 (0.22) ^‡

0.21 (0.18) ^‡

30 (1.72) ^§

26 (1.2) ^§

Skinfolds

4.6 (1.3) ^§

2.7 (0.6) ^§

Serum

RIA

 Erhardt [32]

Cohort

Europe (eight countries)

41 (48)

45 (52)

6 to 6.9^❢

6; 6.9^❢

15.8(1.1)

15.8 (1)

16.9 (2.7)

13.6 (2.9)

Skinfolds

2.7 (1.5;3.7) ^¶

1.3 (0.8;2.5)^¶

Serum

ELISA

72 (53)

65 (47)

7 to 7.9^❢

7; 7.9^❢

15.9(1)

15.9 (1.2)

16.5 (3.1)

14.5 (3.5)

Skinfolds

2.0(1.4;3.8)^¶

1.7 (1.0;3.3)^¶

Serum

ELISA

 Vitery [39]

Cross-sectional

Colombia

56 (51)

54 (49)

7.9 (1.2)

7.8 (1.3)

16.4(1.8)

16.1 (1.2)

22.4 (4.1)

18.4 (3.5)

Skinfolds

6.9 (5.0)

3.3 (3.7)

Plasma

ELISA

 Haapala [40]

Cohort

Finland

192 (49)

198 (51)

7.6 (0.4)

7.7 (0.4)

− 0.2(1.1) ^†

− 0.2 (1.1) ^†

22.2 (7.4)

17.2 (7.7)

DXA

5.9 (4.2)

4.2 (3)

Plasma

RIA

8 to 10 years

 Byrnes [41]

Cross-sectional

Australia

30(51)

29(49)

8.6 (0.2)

8. 5(0.3)

0.5^†

0.3^†

25.9 (1.1)

18.4 (1.2) ^§

BIA

11.5 (2.2) ^§

6.5 (1) ^§

Plasma

RIA

 Arrowsmith [42]

Cohort

Australia

12(46)

14(54)

7.9 (0.8)

8.3 (0.8)

16.6 (2.2)

18.3 (3.7)

19.9 (4.5)

19.2 (5.8)

Skinfolds

6.2 (3.7)

8.3 (5.6)

Plasma

RIA

 Celi[43]

Cohort

Italy

395

447

8.5(7.2;9.6)^❡

9.4(8.3;10.6)^❡

20.6 (16.1;24.1)

21.5(16.1;24.8)

35.2 (11.1)

31.7 (11.7)

Skinfolds

11.9(5.2;20.6)^❡

9.9(3.8;18.4)^❡

Serum

RIA

 Dencker [44]

Cross-sectional

Sweden

79(46)

91(54)

9.8 (0.6)

10 (0.6)

17.4 (2.7)

17.6 (2.6)

21.9 (8.4)

16.1 (8.3)

DXA

5.3 (4.8)

3.2 (4.2)

Serum

RIA

 Yamborisut [45]

Cross-sectional

Thailand

28 (55)

23 (45)

8.1 (0.9)

8.3 (0.9)

− 0.11^†

− 0.35^†

16.9 (5.6)

12.6 (4.7)

BIA

6 (2.6)

3.7 (2.4)

Serum

RIA

 Metcalf [37]

Cohort

UK

148 (56)

114 (44)

8.9 (0.3)

8.9(0.3)

17.9 (3.7)

16.4 (2.8)

26.4 (13.4) ^ℑ

16.6 (12.7) ^ℑ

DXA

6.7 (7.1)^ℑ

3.8 (3.8)^ℑ

Serum

RIA

147 (56)

115 (44)

9.9 (0.3)

9.9 (0.3)

18.4 (5)

17 (3.1)

26.8 (14)^ℑ

18.9 (15.3) ^ℑ

DXA

8.2 (12.7)^ℑ

4.2 (6.1)^ℑ

Serum

RIA

 Jeffery [38]

Cohort

UK

101 (43)

134 (57)

8.0

8.0

0.53^‡

0.28^‡

30.1 (2.1) ^§

26.6 (1.7) ^§

Skinfolds

5.3 (1.7)

3.2 (1.2)

Serum

RIA

101 (49)

134 (51)

9.0

9.0

0.61^‡

0.38^‡

32.3 (1.8) ^§

27.8 (1.5) ^§

Skinfolds

7.2 (1.9)

4.5 (1.1)

Serum

RIA

101 (58)

134(42)

10.0

10.0

0.62^‡

0.43^‡

33 (1.8) ^§

2.9 (1.6) ^§

Skinfolds

8.0.8 (2.2)

5.3 (1.4)

Serum

RIA

 Nightingale [46]

Cross-sectional

UK

2237(48)

2396(52)

9 to 10^❢

9;10^❢

18.6(18.4;18.7)^❡

18.3(18.1;18.4)^❡

29.9(29.4;30.4)^❡

27.2(26.7;27.7)^❡

Skinfolds

11.5 (11;1)^❡

7.2 (6.9;7.5)^❡

Serum

RIA

 Thillan [47]

Cross-sectional

Sri Lanka

84 (51)

80 (49)

9.1 (0.3)

9.2 (0.3)

14.9(13.7;16.3)^¶

14.6 (13.8;17)^¶

20.7(15.5;27.1)^¶

16.2(12.6;24.1)^¶

BIA

3.7(2.1; 6.6)^¶

2.2 (0.9;5.3)^¶

Plasma

ELISA