Final answer:
Fontanelles are generally not smaller several days after birth; they start to gradually decrease in size over the first year, with the posterior fontanel normally closing within the first few months and the anterior fontanel taking longer up to 18 months.
Step-by-step explanation:
The statement that fontanelles will be slightly smaller several days after birth compared right after birth is generally false. Fontanelles are expanded areas of fibrous connective tissue that separates the bones of the skull in newborns and infants. The timeline for the closure of fontanelles varies. The posterior fontanel typically closes within the first two or three months after birth, and the anterior fontanel may take up to 18 months to close. Right after birth, the fontanelles might be larger due to the pressure of passing through the birth canal, and they provide flexibility to the skull. The fontanelles begin to decrease in size more gradually over the first year as the bones of the skull grow and ossify, eventually forming sutures.