When the soft spot goes away too early

Several readers have expressed concern about the soft spot, so I'll elaborate on your question before I answer you directly.

The ‘soft spot’ is the area on top of the head where the bones of the skull have not quite joined. During pregnancy, the skull develops like a sort of jigsaw puzzle; it's not all one bone, but rather many bones that eventually meet and fuse. Some bones meet and fuse before the baby is born. Others fuse after birth to allow room for the brain's tremendous growth during the first year. More than 50 per cent of the total growth of the head occurs in this first year of life. If all the bones fused early, there would be no room for the brain as it grows.

There are often several ‘soft spots’ present at birth, but most are so small and last for such a short time, that parents are unaware of them. But by two months, only two of these spots should be present:

• The smaller is the posterior fontanelle, on the back part of the top of the head. It's usually difficult to find at two months and should be completely gone (because the bones have fused) by four months
• The anterior fontanelle is the one most parents recognise as the soft spot. It's on top of the head toward the front. Four bones come together at this spot, but, because of their rounded corners, they don't quite meet. This soft spot may close as early as nine months or as late as two years. The average is between 12 to 14 months.