Table 1 Characteristics of participants

Child characteristics

Sex (% boys)

4186

50.2

46.5

46.2

46.8

49.7

57.9

40.0

50.2

0.35

Age (months)

4282

36.5 (1.2)

36.6 (1.1)

37.1 (2.4)

36.9 (1.4)

37.2 (2.0)

36.8 (1.4)

36.9 (1.6)

37.2 (1.8)

<0.001

Birth weight (grams)

4184

3511.2 (551.4)

3468.8 (539.0)

3196.0 (520.9)

3247.1 (563.0)

3483.7 (518.1)

3254.7 (559.5)

3067.7 (476.9)

3391.8 (519.5)

<0.001

Gestational age at birth (%≤36 weeks)

4282

4.6

5.3

9.0

1.1

3.9

3.8

4.7

4.8

0.46

Socio-economic characteristics

Age mother at intake (years)

4282

32.2 (4.0)

31.6 (4.3)

28.3 (5.4)

29.6 (5.3)

28.9 (5.1)

30.9 (5.9)

28.7 (5.4)

28.2 (5.3)

<0.001

Educational level

4212

High (%)

66.9

66.6

25.6

12.5

16.0

23.7

20.2

15.0

<0.001

Medium (%)

31.7

28.4

65.4

64.8

57.6

65.8

69.0

49.1

Low (%)

1.4

5.0

9.0

22.7

26.4

10.5

10.7

35.9

Marital status (% single)

4187

5.0

5.6

40.3

40.0

5.3

44.9

22.4

5.3

<0.001

Family income

3584

>2000 (%)

85.6

77.1

27.9

16.9

18.7

34.5

37.1

21.3

<0.001

1200-2000 (%)

11.4

16.8

31.1

33.8

38.3

31.0

30.0

40.0

<1200 (%)

3.0

5.5

41.0

49.4

43.0

34.5

32.9

38.7

Parity (% nulli)

4167

60.3

62.0

67.5

42.9

40.5

55.8

56.5

46.6

<0.001

Family functioning and parenting characteristics

Prenatal maternal psychopathology ¹

3435

0.1 (0.2)

0.2 (0.2)

0.2 (0.5)

0.3 (0.7)

0.3 (0.5)

0.2 (0.3)

0.3 (0.4)

0.4 (0.6)

<0.001

Postnatal maternal psychopathology ¹

3732

0.1 (0.2)

0.1 (0.2)

0.2 (0.3)

0.2 (0.4)

0.2 (0.4)

0.2 (0.2)

0.2 (0.5)

0.3 (0.5)

<0.001

Prenatal family functioning ¹

3838

1.3 (0.6)

1.4 (0.7)

1.7 (0.8)

1.9 (0.4)

1.8 (0.8)

1.6 (0.8)

1.9 (0.7)

1.7 (0.8)

<0.001

Parenting stress ¹

3817

0.2 (0.3)

0.3 (0.4)

0.3 (0.3)

0.3 (0.5)

0.3 (0.4)

0.2(0.3)

0.3(0.4)

0.5(0.5)

<0.001

Harsh parenting (above cut-off)

Maternal report (%)

3543

14.6

19.3

30.4

22.7

24.7

19.0

27.0

16.8

<0.001

Paternal report (%)

4251

13.2

22.1

23.7

23.4

18.7

21.1

27.7

18.5

<0.001