Physical milestone typically refers to your child's weight and height. On average for boys, the average weight would be 29 to 34 pounds and for height 36 to 39 inches. And for girls, the average weight is 28 to 33 pounds and for height 36 to 38 inches. While these are just averages your child may fall under or above these ranges and it may not be a concern, however, you should still discuss this with your child's pediatrician and make sure that your child is developing on track.
While you may notice that in the playgrounds or at school your child maybe shorter or taller than others and you may be concerned as to why that is and you know, you may think to yourself well, I don't recall being taller or shorter than anybody else. I feel that I was average. I don't know why 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 your 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.