These are the areas on the top middle of a baby’s skull that are covered by membranes and skin but not yet by bone. They are also called the ‘soft spots.’ The anterior fontanel is located in the front of the skull just above the forehead. It is the largest soft spot and should be closed by about 18 months. Babies with untreated congenital hypothyroidism may have very large fontanels that are delayed in closing.