I see a lot of books and even doctors seem to talk about percentile charts. What are these charts?


Percentile charts record a baby's weight and height from birth and help in understanding a baby's growth and a range of measurements that are considered normal. Health professionals use them to evaluate your baby's growth. Along with length and weight, your baby's head circumference is also plotted on percentile or centile charts. These charts are graphs which have printed 'centile curves' derived from measuring large numbers of babies and children of a certain population. If your baby is on the 25th percentile curve this means that 75% of all babies weighed are heavier and taller and the remaining 25% are lighter than your baby; if your baby is on the 97% percentile, 3% of other babies her age are taller and heavier than her while 97% are smaller.


Sometimes this concept is hard to grasp and understanding it visually may help. Suppose your baby is in a room full of babies her age. If she is on the 5th percentile, most of the other babies in the room will be bigger than her but if she is on the 95th percentile she would probably be one of the biggest babies in the room. But let's not forget a baby's growth is largely dependent on family genes. Hence it doesn't matter which percentile your baby is on as long as your baby's growth is consistent with the weight and length in good balance. Baby's heads are measured also because the rapid growth in the first year helps paediatricians keep tabs on your baby's growth rate.