Can anyone point me in the direction of a chart that would take gestational age at birth into consideration when plotting growth?

From SGA specific info I've found P was under the 3% for head & weight at birth but when I chart her it puts her up at 13% for her weight (still under 3% for head) so it looks like she drops weight % dramatically in the first couple of months which in reality she came up.

I know I can keep both sets of info on hand, I'm just wondering if anyone has a resource that takes gestational age into account for charting so I can keep it all in one place?...