Table 1. Clinical characteristics of 11,898 healthy reference Chinese children aged 0∼3 years.

Variable	Mean ± SD or n (%)
Male sex	6592, (55.4%)
Gestational age at birth, weeks	39.6±1.3
History of Breastfeeding	10,066(84.6%)
Age at the examination, months	9.27±7.60
Weight, kg	9.13±3.33
Weight-for-age Z scores	0.12±0.07
Height, cm	70.0±11.1
Height-for- age Z scores	0.09±0.06
Maternal pregnancy weight gain, kg	16.4±7.8
Maternal pregnancy calcium supplement use	7,590 (63.8%)
Birth weight, kg	3.232±0.469
Birth length, cm	49.6±5.3
Daily milk and/or breast milk intake, mL	750±251
Outdoor activity duration, h/d (in spring or autumn)	4.1±2.3
Physical activity duration, h/d	1.3±0.8
Calcium supplement use	3,926(33.0%)
Vitamin D supplement use	11,303(95.0%)