Changes to Your Baby's Head

By Cara Familian Natterson, MD

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Here's a description of the changes that take place with regard to your baby's head.

Head shape
In order for a baby to be able to travel through the birth canal, the head must be small enough and flexible enough to fit.

Fortunately the brain is only a fraction of its adult size at birth. The bones that surround it are also able to mold into different positions. This explains why most babies that have been resting low in their mother's pelvis, waiting for delivery, have long pointy heads just after birth.

While the head must be extremely moldable, it must also be very sturdy. The skull is responsible for protecting the brain beneath it. It must be strong enough to endure bumps and bonks during delivery and thereafter.

And, in order to grow and develop complex language and thought, the brain and its surrounding skull must be able to expand.

Therefore both the brain and its protective shell are designed to change shape and grow over time. For something so hard to the touch, the bony skull is amazingly malleable.

Head growth is greatest in the first year of life. As the skull grows, it changes shape. Therefore, when a baby is placed in various positions over and over again, the pressure on one particular part of the skull can cause flattening of that area.

While children and adults have relatively fixed head shapes, babies do not. The range of skull shapes and the speed at which the skull changes shape are remarkable.

POINTED HEAD (MOLDING)
(Birth)

What is happening inside my baby's body?
The bones that make up your baby's skull are designed to move around so that the head can pass through a tight space when the baby is born. In fact the skull bones look like big pieces of a puzzle: they fit together, but they are not firmly attached.

When a baby hangs upside down and low in her mom's pelvis for days (or weeks), the bones of her skull mold to fit the mom's pelvis. This is why many newborn babies have pointed heads ? a phenomenon called molding. This is a good strategy for a delivering baby because it may help her to pass through a very narrow birth canal.

Some babies do not hang upside down in the pelvis for long (or at all), so they have perfectly round heads at birth. This is especially true among babies born by cesarean section.

The fact that the bones of a baby's skull can move around allows humans to have rapid brain growth, not just while developing inside the womb but after birth as well. In the first two years of life, the human head grows an average of 40 percent, allowing a newborn to be delivered while her brain is still quite immature. In fact humans are the only species born with brains that are so immature that a baby is entirely dependent upon a parent.

Think of horses - they are able to walk within hours of birth. Humans cannot even crawl yet. Why does this happen? Because humans are born with immature brains that can ultimately develop a level of sophistication that no other animals have.

Again, this is all thanks to a moldable head and movable skull bones. The only alternative in evolution allowing for massive human brain size and sophistication would have been for moms to have gigantic hips!

Molding lasts only a few days after the baby is born. Remarkably the head rounds itself out quickly once a baby has been delivered. Within a week the head assumes a standard round shape, with a soft spot at the very top toward the front and another, smaller soft spot at the top toward the back.

Soft spots
These spots - called fontanels - are simply normal spaces between the bones of the skull. They allow for even more growth of the brain and skull after birth. The fontanel at the back of the head typically closes between two and twelve weeks of life; the one at the top of the head usually closes sometime between six and 18 months of age.

What can I do?
Parents do not need to do anything to resolve molding. The head will usually round itself out. However, in some cases, parts of the skull become flat over time. To avoid this, you should put your baby down to sleep on her back, with the head in slightly different positions throughout the day and night.