A the birth, your baby’s skull bones are not welded and are separated by linear spaces that you can follow with your finger: these are the sutures. At the confluence, by being very careful, we can find membranous spaces. These are the fontanelles. We do not know, but at birth, the baby has six, four of which almost close in the first days. They are so tiny, in fact, that you won’t even see them. Except, perhaps, the small fontanel or “lambdatic”, triangular in shape, which is behind the skull of the newborn. But it closes very quickly, you will only be able to feel it until you are 2 or 3 months old. As for the large fontanel, you will not fail to see it and touch it regularly, on the top of your baby’s head, between the two parts of the frontal bone. Especially since your child does not have a lot of hair! It is the anterior fontanelle or “bregma”, recognizable by its diamond shape. It measures about 3 cm and stays open longer: up to 15-18 months.
Sometimes when the baby cries or gets angry, it appears briefly, as a protrusion. It is caused by the fact that the central vein below swells with blood under stress. You may also have the impression that it is lowering a bit, just before feeding, when the baby is hungry. Or you can see that it is tense and level. Don’t worry, this is the normal condition of this area, due to your baby’s movements. He’s not dehydrated. Simply, when he is standing, for example, the blood does not swell that same central vein. If you put your child to bed, it will regain its usual flat, supple and firm appearance.
You must consult quickly if …
- The fontanel is domed. This phenomenon can occur whenever the child has a fever.
- It is hollowed out. She marks the hollow of her finger. They say she is depressed. It could be dehydration. But in this case, the baby presents other symptoms: absence of tears, dry diapers, dark circles, “cardboard” skin…
They facilitate brain growth
These membranes play a very important role. First, at the time of childbirth: by allowing the overlap of the sutures of the skull, which reduces its volume. Hence the bizarre appearance of the skull of some newborns, in sugar loaf or in shells with, sometimes, a lump due to the pressures undergone during childbirth. Rest assured, the bones are very malleable and your baby’s head will take a normal form within 24 to 48 hours of birth. Then, the large fontanel, elastic tissue, will especially contribute to the good development of the brain. It will adjust to its growth, and you will see your baby’s fontanel shrink month after month until it is completely gone. It is this that the doctor feels, at the same time as the bones of the skull, since its evolution depends on that of the bone sutures. “In some children, this closure is slower, which is why it is necessary to monitor its progress”, explains Professor Vittu. A check that counts especially during the first two years, because it allows to detect too rapid growth, therefore hydrocephalus or, on the contrary, deficient, linked to the too early closure of bone sutures. This is called craniosynostosis, a deformation of the head on the sides, in width and in length. Or a deformation in the forehead which gives the face a triangular shape. This abnormality can be corrected later with surgery, when the child is older.
Babies with small or large heads!
In addition to this usual palpation during each visit, from birth to 2 years old, the doctor sacrifices to the essential ritual of the measurement of the cranial perimeter, using a tape measure. He reports these measurements on the curves provided in the health record. In summary, this growth of the skull is very important during the first year, a little less the second and even less the third. More precisely, the cranial perimeter goes from 35 cm on average at birth to 44 cm at 6 months, 47 cm at 1 year, 50 cm at 2 years, 51-52 cm at 3 years. After this age, the skull will continue to grow, but very slowly: about 5 cm until adulthood.
It is possible that in case of abnormality or particularity, the doctor also measures your head circumference in order to compare it with that of your child. “There are some families who have a big head or a small head,” he continues. Simply ! Finally, it is again the large fontanel that the doctor will be able to sweep with an ultrasound probe to, if necessary, precisely assess the evolution of the skull. We call this examination “transfontanellar ultrasound”. Painless, very easy to achieve because the skin is thin and permeable to ultrasound, it is especially practiced in premature babies and babies with a large head.
No problem for the shampoo!
Even if you are moved to discover your baby’s heartbeat there, do not be intimidated by this apparent vulnerability … If he has cradle cap, choose a specific shampoo and rinse thoroughly to reduce their appearance. Daily grooming does not risk damaging it.