Physical milestones refer to your child's height and weight. Typically by the age of six and seven your child should be around 41 to 56 pounds for boys, and 44 to 49 inches tall. For girls, the average weight would be between 40 and 56 pounds and 43 to 49 inches tall.
While your child's height and weight may fall below those ranges, or even above those ranges and they may be okay, it is important to discuss this with your child's pediatrician so that you can track your child's development, and make sure that they are developing appropriately.
While you may notice that in the playground or at school your child maybe shorter or than others, and you may be concerned as to why that is, and you may think to yourself " Well, I don't recall being taller or shorter anybody else. I feel that I was average, I don't know what my child is." It's okay. Kids develop at a different rate, and sometimes girl even develop faster than boys typically, and they might even catch up to boys.
So what's really important is that you're monitoring how your child is growing in terms of weight and height, and that means that speak with your pediatrician, and make sure that you have a copy of their growth chart so that you too can continue to monitor your child's growth and height.