Table 1.

Baseline characteristics among children aged 6–17 years in urban Guangzhou, China

	Total	Boys	Girls	P value
Demographics
No. of participants	18,302	8624	9678	–
Age (years)	11.32(3.16)	11.29(0.04)	11.49(0.04)	0.001
From Northern area (%)	40.4	40.5	40.2	< 0.001
Monthly income of  Family (%)				0.012
≤ 5000 yuan	30.5	29.8	31.0
> 5000 yuan	13.9	13.5	14.4
Not willing to answer	55.6	56.7	54.6
Mother’s education year  (%)				0.01
≤ 9	43.7	55.0	51.9
10–12	20.4	25.6	25.6
13–16	11.9	11.0	12.6
≥ 16	9.8	9.8	9.8
Puberty on-set (%)	56.1	43.4	65.2	< 0.001
Height(cm)	147.26(16.12)	148.95(0.22)	146.93(0.21)	< 0.001
Weight(kg)	39.46(12.57)	40.56(0.17)	39.29(0.16)	< 0.001
BMI	17.73(2.26)	17.65(0.03)	17.73(0.03)	0.078
Dietary intake (servings/day)
Fruit	1.27(1.06)	1.25(0.01)	1.30(0.01)	0.006
Vegetable	1.79(1.40)	1.81(0.02)	1.79(0.02)	0.27
Meat	1.17(1.21)	1.32(0.02)	1.02(0.02)	< 0.001
Sugar beverage	0.41(0.74)	0.50(0.01)	0.33(0.01)	< 0.001
Physical Activity (PA)
HLPA (hour/day)	0.47(0.69)	0.61(0.01)	0.45(0.01)	< 0.001
MLPA (hour/day)	0.48(0.72)	0.53(0.01)	0.44(0.01)	< 0.001
Walking (hour/day)	0.78(1.13)	0.84(0.02)	0.74(0.02)	< 0.001
Sedentary (hour/week)	39.38(25.72)	38.40(0.35)	40.05(0.02)	< 0.001
Sleep duration (%)
< 7 h	18.3	16.8	19.6	< 0.001
7–9 h	57.3	57.8	56.9
> 9 h	24.4	25.4	23.5

Continuous variables are displayed as mean (standard error, for boys and girls) and mean (standard deviation, for total), categorical variables are displayed as proportion. P values are from T-tests (continuous variables) and chi-square tests (categorical variables) between boys and girls

BMI body mass index, PA physical activity, HLPA high level physical activity, MLPA middle level activity