Monitoring your baby’s growth and watching them develop and gain weight is a wonderful part of pregnancy. But this data is not collected just so we can delight in each stage. In reality, it is essential for assessing whether the pregnancy is progressing as expected and if everything is okay with the baby1.
Right after birth, the baby is assessed by the pediatrician who is closely monitoring the delivery along with the obstetrician. The collected information is recorded in a document that will be given to the parents at discharge, containing information on weight, length, and head circumference, as well as the type of delivery performed. This is the first set of information that will be recorded in the baby’s growth chart, which will be followed at least until the age of three.
In addition to the baby’s growth chart, pediatricians use reference charts for monitoring each age group, including height measurements and the calculation of the child’s potential adult height. This chart is known as a percentile chart and is used to see which percentile the baby or child is in.
During the pediatrician visit, the baby will be weighed and measured to monitor in the chart how their growth and development are progressing2. This curve is plotted on the standard chart from the World Health Organization (WHO), which is updated to keep up with the physical changes in the population worldwide. Your baby’s curve does not have to be exactly the same as the WHO’s, but it’s important for it to be close to what is considered healthy. Something that should be investigated is when the curve is very different from what is expected based on the baby’s growth chart.
Weight and Length Chart for Boys
| Age (months) | Length | Baby’s Weight |
| Newborn | 50 cm | 2,900 to 3,300 grams |
| 1 month | 55 cm | 3,700 to 4,200 grams |
| 2 months | 57 cm | 4,300 to 5,000 grams |
| 3 months | 61 cm | 5,000 to 5,700 grams |
| 4 months | 62 cm | 6,300 grams |
| 5 months | 63 cm | 6,900 grams |
| 6 months | 64 cm | 7,500 grams |
| 7 months | 66 cm | 8,000 grams |
| 9 months | 69 cm | 8,900 grams |
| 10 months | 71 cm | 9,300 grams |
| 11 months | 73 cm | 9,600 grams |
| 12 months | 75 cm | 10,000 grams |
Weight and Length Chart for Girls
| Age (months) | Length | Baby’s Weight |
| Newborn | 48 cm | 2,500 to 3,200 grams |
| 1 month | 52 cm | 3,200 to 4,000 grams |
| 2 months | 56 cm | 4,000 to 4,700 grams |
| 3 months | 59 cm | 4,700 to 5,500 grams |
| 4 months | 61 cm | 6,100 grams |
| 5 months | 62 cm | 6,700 grams |
| 6 months | 63 cm | 7,300 grams |
| 7 months | 65 cm | 7,800 grams |
| 8 months | 67 cm | 8,200 grams |
| 9 months | 68 cm | 8,600 grams |
| 10 months | 70 cm | 9,100 grams |
| 11 months | 72 cm | 9,500 grams |
| 12 months | 73 cm | 9,800 grams |
That is why it is extremely important to have ongoing follow-up with a pediatrician to assess your baby’s development. For mothers who tend to compare their baby’s weight and length with others, remember that each baby and child develops in their own way and grows differently, in addition to family genetics, which also varies and influences growth. Therefore, just because your baby is thinner or smaller than another does not mean they are outside the normal range!
Now, if a decrease in the growth curve is found in the baby’s growth chart, the pediatrician will analyze issues related to feeding and advise on the best way to resolve the situation. Feeding schedules, such as breastfeeding, or the type of milk being given to the baby, as well as when new foods are introduced, should all be reported to the pediatrician so that they know how the baby’s system is responding at each stage. If necessary, the pediatrician may request additional tests for a more detailed check.
*The values in this chart are approximate and are an estimate. Talk to your pediatrician if the differences are very significant.
See also: Pregnancy size and weight chart
