The posterior fontanel, the soft spot on the back of your baby’s head, will close first. It is the smaller of the two fontanels so it doesn’t take as long to close. It normally closes by the time your baby is 2-4 months old.
"The idea is to bring the posterior fontanel forward from the 3, 6, or 9 o'clock position to the 12 o'clock position. Then the baby is more deliverable. In the right-sided position, you rotate it clockwise. In the left-sided position you should rotate it counterclockwise.
There are usually two soft spots in the skull of a newborn, the anterior and the posterior fontanelle. The posterior fontanelle will close by about 2 months of age. The anterior fontanelle usually closes between 9 and 18 months of age.
The one on the back of her head is called the posterior fontanelle. It's usually smaller than the other and triangular in shape. The one on the top of her head is the anterior fontanelle. It is larger and diamond or kite-shaped.
The posterior fontanelle, on the back of the head, is a small triangle shape that usually closes by the time your baby is eight weeks old. The anterior fontanelle, on the top of the head, is a larger, slightly sunken diamond shape.
Growth rate is still significant, but not as rapid as in the first 2 months
Posterior fontanelle ("soft spot") closes
Movement and Activity ...
The anterior fontanel is about two inches wide and may not be closed completely until your baby is 18 months old. The posterior fontanel is only about a half inch wide and will be closed by the time your baby is three months old, much earlier than the anterior soft spot.
The fontanelles allow for the skull bones to give slightly during birth, and will gradually fuse together of their own accord - over a period of weeks for the small posterior fontanelle, and by 18 months for the larger anterior fontanelle at the top of baby's head.
One of two soft spots on the new baby's skull, where the skull bones have not yet fused. The anterior fontanelle on the top of the head is large and diamond-shaped, and closes at around 18 months. The smaller, triangular posterior fontanelle is at the very back of the head and closes at about six ...
See also: What is the meaning of Anterior, Posterior, Fontanel, Pregnancy, Hormone?