When is the Latest for a Baby’s Fontanelle to Close?

A baby’s fontanelle, typically measuring 1.5 to 2.0 centimeters at birth, expands as the head grows in the first few months. Generally, it starts to shrink around 6 months after birth and closes completely by about 18 months. The posterior fontanelle, a triangular space between the occipital and parietal bones at the back of the head, usually closes within 6 to 8 weeks after birth.
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