When you take your child to the doctor, the doctor will weigh her and measure her height, then compare this reading with a growth chart to determine whether your child is growing appropriately. Her weight and height will be compared with those of children her age to establish what percentile she falls in.
Most children grow on course, and it really doesn't matter what percentile they are in as long as they thrive and develop.
When it comes to percentile ranking, being in a higher bracket isn't necessarily an accomplishment, nor does such a result automatically predict how big or small a child will be when she grows up. As long as good, nutritious food is provided to them, children will eat enough to grow well.