What are percentiles?

Percentiles and growth charts are tables where the normal growth of healthy infants is illustrated. There are 5 ascending curves marked on the table corresponding to each percentile: 3rd, 15th, 50th, 85th, and 97th.

Occasionally, babies do not follow the weight percentiles in which they are born or even drop in percentiles throughout their growth. It is important to note that percentiles do not tell us whether a baby is healthy or not, but they simply reflect the evolution of the weight and height of babies and children.

These curves are simply a statistical representation of normality when it comes to the weight and height of babies. And so, it is just as normal for a healthy child to be in the 3rd percentile as it is in the 90th percentile. And it is just as healthy for a baby to be in the 15th percentile as for a baby to be in the 97th percentile. Everyone, babies, children, and even adults, is different and has a different individual complexion because we all have different fathers, mothers, and different genes.

The history of growth charts

Some years ago, the percentiles and growth charts that were used to assess the growth of babies were old tables from the ’60s, based on American children (only) who were bottle-fed and who were introduced to complementary solid food at only a few months old, because they had nutritional deficiencies due to formula milk that lacked in nutrients.

In 2006, the World Health Organization (WHO) published new growth charts with new percentiles that were now more accurate because they were made with breastfed infants from six different countries.

Do percentiles represent the evolution of my baby’s growth?

No, the percentiles that we see shown (the curves on the graph) are not the exact representation of the real growth of a baby because children do not grow in such a regular and perfect curve. The growth curve that we see in the growth chart is the result of the statistical gathering of the data to simply them when you look at the chart. In reality, percentiles and the evolution of growth of a child would translate into a graph with irregular steps. Therefore, a slight drop in percentiles is absolutely normal. However, a dramatic drop in percentiles during a few months, such as, for example, a drop from the 80th percentile to the 15th percentile, is a completely different situation.

It is also important to understand that the percentile in which a baby is born has nothing to do with the evolution of the baby’s weight. Many babies are born with a considerable weight, but then they normalize their growth, and there is no reason for them to always remain in the high percentile in which they were born.

Furthermore, not only the weight percentile should be considered, but it is also necessary to assess the height percentile of a baby and make sure that both growth evolutions are in line with each other.

Are you worried about something else?

If you have any other questions and worries about your baby’s growth, or if you think you might need supplementing with formula or any other breastfeeding-related issue, you can download the LactApp app for free for Android and iPhone and find more information as well as a consultation channel where you can write to our experts.