Babies come in various sizes, and it really does not matter what percentile is their length and weight, as long as their measurements are on the chart and progress smoothly over time.
Your baby's health care provider will measure his length, weigh, and head circumference during each well visit. Then, these measurements will be plotted on standardized growth charts. Over time, the curve for the length, weight, and head circumference should be smooth, meaning that your child progresses with growth appropriately.
The individual CDC growth charts specific for age and sex are available at: