My daughter was born at 3pounds 3 ounces at 33 weeks, and was 16 pounds at one year. She has always been between the 3 and 5 percentile on the charts. It has been a battle trying to keep weight on her. But I think it is more genetics then anything with her. Her dad is 6'3 and 165 pounds, and I am 5'2 and 105. So we are both naturally very skinny. But I am very proud to say that at the start of kindergarten their was one girl shorter then Brianna, but I am sure she still weighed quite a bit more. For her school physical this fall my 5 1/2 year old hit 31 pounds for the first time. She is finally wearing 4-5t. But this is for the length only. As long as she is growing evenly then I doubt there is anything to worry about. Like if the height, weight and head stay with in the same curve, and she doesn't and any extended periods of no growth, and stays somewhat is the same percentages then everything is probably fine.