What does 90th %'tile mean?

Smootchy

? Lo is in the 90% and I don't know what that means

lindylogana

It means 90% of babies are as big as or smaller than your baby.  And 10% of babies are bigger than yours.

lindsaynjason

It means he's bigger than 90% of babies in that category (weight, length, etc...)

carter51

It means that 10% of babies are smaller than him for whatever measurement you are referring to. My pediatrician gives me growth charts for weight, length, and head circumference at each appointment. So for example, LO was in the 75th percentile for length so he is longer that 75% of babies his age. Only 25% of babies 2 months old are longer than him.

Often with growth charts and percentiles, they are looking more that they stay on a nice curve and don't jump around (like go from the 50th% one month, to the 10% the next or something)