My DD has always been on the small size (in the shaded section) HV has rung me up several times when we first moved to the practice ,when she was about 2.5 to come and weigh her .In the end I told her catagorically that I was really not concerned as she was growing taller at a steady rate even iof she wasn't gaining much weight.She eats very little and loves grapes apples oranges and raw sald.Which is not great if you are underweight.I've just checked her weight on NHS UK she is 4 yrs and 5lbs and weight exactly 2st which puts her on the first centile.
What actually are the risks of a child being underweight but obviously growing upwards