Table 1 Characteristics of mother–child pairs according to infant feeding modalities

Number of subjects (%)

5934 (10.0)

35,374 (59.4)

18,256 (30.6)

Maternal characteristics

Maternal age at term delivery, years

28.1 ± 4.1

27.6 ± 4.3

27.9 ± 4.2

 < 0.001

Prepregnancy BMI category, %

0.002

 < 18.5 kg/m²

15.5

14.0

13.2

 18.5 ~ 23.9 kg/m²

60.6

63.3

64.4

 24.0 ~ 27.9 kg/m²

17.0

17.2

16.9

 ≥ 28.0 kg/m²

6.9

5.5

5.4

Education, %

 < 0.001

 ≤ 9 years

18.1

30.3

25.6

 > 9 ~  ≤ 12 years

20.4

18.6

17.5

 > 12 ~  ≤ 16 years

58.5

47.6

51.7

 > 16 years

3.0

3.5

5.2

Smokers, %

1.4

1.2

0.9

0.001

Gestational diabetes at term pregnancy, %

7.0

4.9

5.5

 < 0.001

Child characteristics

Sex, %

 < 0.001

  Boys

54.6

51.6

51.7

  Girls

45.4

48.4

48.3

Birth weight, g

3347 ± 493

3390 ± 447

3393 ± 440

 < 0.001

Birth weight category, %

 < 0.001

 < 2.5 kg

3.7

1.9

1.6

 2.5 ~  < 4.0 kg

88.9

91.1

91.3

 ≥ 4.0 kg

7.4

7.1

7.1

Gestational age at delivery, weeks

39.4 ± 1.6

39.6 ± 1.5

39.6 ± 1.4

 < 0.001

Z-scores for body mass index for age

 1 Years old

0.69 ± 1.0

0.69 ± 1.0

0.63 ± 1.0

 < 0.001

 2 Years old

0.64 ± 1.0

0.62 ± 1.0

0.56 ± 1.0

 < 0.001

 3 Years old

0.32 ± 1.1

0.31 ± 1.0

0.26 ± 1.0

 < 0.001

 4 Years old

0.22 ± 1.1

0.22 ± 1.1

0.19 ± 1.1

0.012

 5 Years old

0.21 ± 1.2

0.23 ± 1.1

0.20 ± 1.1

0.035

 6 Years old

0.28 ± 1.4

0.29 ± 1.3

0.26 ± 1.3

0.038