help with percentile of premature baby

[Bala123]

My baby was born at 36 weeks because of preclampsia, his birth weight was 3 pound 14 ounce ( 1.7 )kg. Today he is exactly 4 months old that is 17 weeks but if i’ll Do his correct age he is 13 weeks.can anybody help me with telling on which percentile he is right now. Today I checked his weight he is 5.70 kg
I have attached his percentile chart in his red book.. plz help me with that.. thanks in advance

 

[Surveyor]

At 13 weeks that would make him square in the 9th percentile on that chart, but if you are measuring him as a 17 week-old it looks like he is in the 2nd percentile (all according to the chart). This means that 91 out of 100 13-week-old babies are larger than him, and 98 out of 100 17-week-old babies are larger than him.

-Sev