Table 2 Characteristics of participants stratified by sex and rapid weight gain from birth to 1.5 years

 Age, years

29.7 ± 4.5

29.1 ± 4.7

0.35

29.1 ± 5.5

28.6 ± 4.6

0.52

 Gestational age, weeks

39.2 ± 1.1

38.6 ± 1.1

< 0.01

39.2 ± 1.0

38.6 ± 1.1

< 0.01

 Length z-score

0.30 ± 0.8

− 0.09 ± 0.89

< 0.01

0.34 ± 0.85

− 0.05 ± 0.93

< 0.01

 Weight z-score

0.47 ± 1.0

− 0.16 ± 0.86

< 0.01

0.27 ± 0.79

− 0.47 ± 0.88

< 0.01

 Height z-score

0.26 ± 0.8

0.82 ± 0.99

< 0.01

− 0.03 ± 0.99

0.65 ± 0.96

< 0.01

 Weight z-score

0.05 ± 0.7

1.11 ± 0.92

< 0.01

− 0.03 ± 0.79

1.03 ± 1.03

< 0.01

Change in weight z-score from 0 to 1.5 years

− 0.42 ± 0.76

1.28 ± 0.46

< 0.01

− 0.30 ± 0.63

1.50 ± 0.69

< 0.01

 Height z-score

0.17 ± 0.86

0.62 ± 0.83

< 0.01

− 0.16 ± 0.91

0.19 ± 0.96

< 0.01

 Weight z-score

0.02 ± 0.89

0.59 ± 1.06

< 0.01

− 0.20 ± 0.94

0.32 ± 0.86

< 0.01

 BMI, kg/m²

18.8 ± 2.6

20.1 ± 3.2

< 0.01

19.2 ± 2.5

20.4 ± 2.8

< 0.01

 WC, cm

67.5 ± 7.1

71.3 ± 9.0

< 0.01

67.6 ± 6.3

70.0 ± 6.8

< 0.01

 Fat mass index, kg/m²

2.8 ± 1.5

3.4 ± 1.6

0.01

4.4 ± 1.5

5.1 ± 1.6

< 0.01

 Body fat percentage, %

14.2 ± 5.0

16.1 ± 5.3

0.01

22.4 ± 4.8

24.3 ± 4.8

< 0.01

 Lean mass index, kg/m²

15.6 ± 1.4

16.3 ± 1.9

< 0.01

14.4 ± 1.3

14.9 ± 1.4

< 0.01

 Overweight, N (%)

12 (8.8)

15 (22.1)

0.01

9 (6.7)

11 (13.1)

0.15

  < 2 h

82 (59.9)

46 (67.6)

0.32

74 (55.2)

45 (53.6)

0.27

  2–3 h

30 (21.9)

15 (22.1)

42 (31.4)

21 (25.0)

  ≥ 3 h

25 (18.2)

7 (10.3)

18 (13.4)

18 (21.4)

  Age < 12 years

34 (24.8)

22 (32.4)

0.32

79 (59.0)

66 (78.6)

< 0.01

  Age ≥ 12 years

103 (75.2)

46 (67.6)

55 (41.0)

18 (21.4)

  SGA

3 (2.2)

7 (10.3)

< 0.01

1 (0.7)

9 (10.7)

< 0.01

  AGA

100 (73.0)

51 (75.0)

101 (75.4)

65 (77.4)

  LGA

34 (24.8)

10 (14.7)

32 (23.9)

10 (11.9)