Physical growth index measurement
Height and body weight of all the subjects were measured, and fixed personnel was assigned to measure the height and body weight. The subjects wore shirts or thin sweaters (air-conditioned rooms) and took off their shoes. Their height was measured by a vertical altimeter, accurate to 0.1cm, and their weight was measured by an electronic scale, accurate to 0.1kg. Gender and birth date of the children were recorded at the same time.