I asked Veena the purpose of her appointment. She said “ Doctor - I was in a function yesterday and my relatives looked at my baby and said - Veena - Are you not feeding her, she seems so skinny. I felt very guilty and wanted to see you immediately. Doctor - Is my baby doing good? I hope there is nothing wrong with my baby.

I looked at Veena and said - Veena - Do you have the growth chart with you? Look at the Growth chart. Baby’s weights are usually measured and plotted at birth, 6, 10 and 14 weeks, 9 months, 15-18 months to monitor growth. The height, weight and head circumference are also measured up to 3 years of age. In Veena’s case the baby was born with a birth weight of 2.8 kgs. Now at 5 months he weighs 7.8 kgs which is almost more than 50th percentile, Which is very good. At 3 months he was 5 kgs in weight. So he has been gaining weight steadily and has always been in the 50th percentile weight. So this is not bad at all. Don’t get worried. As long as the baby is gaining weight and is also gaining height, and following the growth curve and is parallelling one of the growth percentile lines, one should not be worried. That means he is getting enough calories. If the weight begins to fall or dips below 2 percentiles- for ex- If the baby was initially in the 75th percentile and in 2 months his weight has steadily fallen to 25th percentile, then it is a cause for concern. It is the same with the height of the baby. As long as he is growing within the same percentile or is increasing it is normal. If the growth in height stops and the baby’s height percentile begins to decline then one has to look for reasons for stunted growth.  

There are separate growth charts for height, weight, and head circumference. These charts simply represent the average height, weight and head circumference of a sample of normal children of different age group and are plotted as a graph. The percentile lines include 3%, 25%,  50%, 75%, 97%. If a child's weight is at the 50th percentile line, that means that out of 100 normal children her age, 50 will be bigger than she is and 50 smaller. Similarly, if she is in the 75th percentile, that means that she is bigger than 75 children and smaller than only 25, compared with 100 children her age.

Why do we use the growth chart?

The growth percentiles by themselves don't say much. What really matters is the rate of growth:

• A normal rate of growth means the child's growth points closely follow a percentile line on the chart.
• If a child's weight, height, or head size is below the 5th percentile, then the doctor will see if she has always been below 5th percentile. If she has always been below 5th percentile and is maintaining that, then that may be her normal. But if she has been way above 5th percentile and has suddenly dipped then it is a cause for concern.

How to Tell If Growth Could Be a Problem

One of the first signs that a child is not getting enough calories is when her weight increases at a much slower rate than her height and begins to fall below two percentile lines.

• Depending on the extent of the poor intake the child's height could become "stunted," that is, the height begins descending on the growth chart.
• If the lack of nutrition is severe and continues for an extended period of time, the head growth slows down, indicating that there are not enough calories for the brain to grow at a normal rate.
• Again no child’s growth chart is a perfect line. There are always dips and highs. Kids can go through some troughs during times of illness. If the child seems happy and playful, she or he may be just fine.

Ref : https://www.indianpediatrics.net/mar2007/mar-187-197.htm