[Key parameters and formulas for approximate average height and weight of normal Chinese children under 7 years of age]

In order to understand the normal physical growth of Chinese children, data of children aged from 0 to 7 years from urban and rural areas of nine Chinese cities in 2005 were analyzed.The original data of height and weight were drawn into growth curves charts by Graphpad Prism 5.0 software according to the different age groups. The children were classified into five age groups: 0-3 months, 4-6 months, 7-12 months, 13-24 months, and 2-7 years.The average birth weight was 3.3 kg and the height averaged 50 cm. The average monthly weight gain was 1.0-1.2 kg and the average monthly increase of height was 4 cm in the 0-3 months group. By 3 months of age, the weight and height averaged 6.6 kg and 62 cm, respectively. In the 4-6 months group, the growth rate was reduced to a half of the 0-3 months group, with an average monthly weight and height gain was 0.5-0.6 kg and 2 cm respectively. The growth rate in the 7-2 months group was a half of the 4-6 months group. By 12 months of age, the weight and height average 9.9 kg and 75 cm, respectively. The average monthly weight and height gain in the 13-24 months group was 0.2 kg and 1 cm respectively, with an average weight and height of 12 kg and 87 cm respectively by 24 months of age. A steady growth was found in the 2-7 years group, with a yearly average weight and height increment of about 2 kg and 7 cm respectively. The formulas for approximate average weight and height in children between 2 and 7 years were as follows: age (yr)*2+8 (kg) (weight); age (yr)*7+75 (cm) (height).The approximate weight and height of normal Chinese children under 7 years of age can be evaluated by the key parameters and formulas above mentioned.