The major stages of physical development in infants
Dr. Valleteau de Moulliac,
Consulting Pediatrician for Laboratoires Sarbec
From the moment your child is born, pay attention, among other things, to their growth, as it is an essential element of medical monitoring. It is indeed an indicator of development, which continues throughout childhood.
It is also a very valuable indicator of overall good health: while common, mild illnesses do not hinder growth, severe chronic diseases always have an impact on it.
Growth depends on genetics, of course, but also on nutrition and environment. But be careful, each child develops at their own pace, and even at the same age, there can be significant differences from one child to another, which is not abnormal (so do not compare); keep in mind that there are standards with averages and variations around those averages. More than a single number on a given day, it is the shape and regularity of the growth curve that matter. Your doctor records all these measurements in the health record, which includes the reference growth curves. You should pay as much attention to your child's height as to their weight. Monitoring head circumference is also important (it is an indicator of brain development).
Milestones in height
| Birth (full term) | 50 cm |
| 3 months | 60 cm |
| 9 months | 70 cm |
| 18 months | 80 cm |
| 2 and a half years | 90 cm |
| 4 years | 1 m |
So, as you can see, by age 4, a child will have doubled their birth height.
Milestones in weight
| Birth (full term) | 3 kg |
| 3 months | 5 to 6 kg |
| 6 months | 6 to 8 kg |
| 9 months | 7 to 9 kg |
| 1 year | 8 to 10 kg |
From 1 year onwards, the weight curve is very regular: the child gains an average of 2 kilos per year, so that they weigh:
- 11 to 12 kg at 2 years
- 13 to 14 kg at 3 years
- 15 to 16 kg at 4 years
Milestones in head circumference
| Birth | 35 cm |
| 3 months | 40 cm |
| 9 months | 45 cm |
| 3 years | 50 cm |
After 3 years, head circumference increases only very slowly, reaching an average of 57 centimeters in adulthood. This helps us understand a key fact about development: the essential part of brain development occurs during the first three years.
Baby teeth
- The first teeth appear between birth and 1 year. While the first tooth eruption is usually seen around 6 months, some children (rarely) are born with one or two teeth, while others won’t see their first tooth until 1 year old: this has no particular significance, and you should not believe there is any link between the age of the first tooth and a child’s precocity.
- The order in which teeth come in is not fixed either. Usually, the lower central incisors appear first, followed by the upper central incisors, then the lateral incisors. Generally, by 1 year, the child has 8 teeth. Around 18 months, the first baby molars (premolars) appear; around 2 years, the canines, which come between the incisors and molars, and after 2 years, the second baby molars complete this first set of teeth, called milk teeth, which includes 20 teeth: for each jaw, 4 incisors, 2 canines, 4 premolars.
