Table 1 Sample characteristics^a,b

Age (years)

15.02 (0.05)

15.03 (0.06)

15.02 (0.04)

Body mass index (BMI)

21.27 (0.10)

20.67 (0.11)

20.99 (0.08)

Household income quartile

 Lowest

11.01

12.64

11.76

 Middle-low

25.23

27.35

26.21

 Middle-high

32.00

30.67

31.38

 Highest

31.76

29.34

30.64

Residence

 Urban area

83.16

82.54

82.87

 Rural area

16.84

17.46

17.13

Maternal weight status

 Underweight

3.62

3.68

3.65

 Normal weight

71.36

70.62

71.02

 Obese

25.02

25.70

25.34

Maternal educational level

 ≤ Middle school

16.71

16.44

16.59

 High school

57.42

56.44

56.96

 ≥ College

25.87

27.13

26.45

Weight control practice

 Lose weight

25.71

47.65

35.90

 Stay the same weight

13.16

16.05

14.50

 Gain weight

18.08

2.95

11.05

 Do nothing

43.04

33.35

38.54

Moderate exercise

 Never

43.70

61.18

51.83

 1-2 days/week

28.40

25.21

26.92

 ≥3 days/week

27.90

13.60

21.26

Feeling under stress

 Very little

16.22

13.03

14.74

 Little

59.09

54.23

56.83

 Much

21.28

27.56

24.20

 Very much

3.40

5.18

4.23

Smoking experience

 Yes

23.52

10.51

17.48

 No

76.48

89.49

82.52

Drinking experience

 Yes

41.24

34.73

38.22

 No

58.76

65.27

61.78