Trudy, hair growth in children varies widely. Some children are born with a lot of hair and others don't grow much until they're 2 or 3. Some babies have hair all over their heads and others have more in some places than others. Also, many babies lose their hair in their first year. In some it grows back right away but in others it takes a while to grow back. Some babies lose their hair on the back of their heads simply from sleeping on their backs. In all, your baby's hair pattern may be completely normal.
However, when an unusual hair growth pattern is associated with other unusual features, such as a fontanel not closing properly, it's a good idea to have the doctor check your baby thoroughly to make sure she doesn't have a medical condition. In most babies, the anterior fontanel (on the top front of the head) closes by 18 to 26 months of age. Although later closure can be normal, and can run in families, it can sometimes be a sign of other medical conditions such as hypothyroidism, skeletal problems, increased pressure in the brain or a genetic syndrome.
Be sure to ask your doctor to check your baby's fontanel and hair pattern. He may also check how your baby's head circumference has grown over time, check her facial and body features, test her development and maybe conduct urine and blood tests and an X-ray or CT scan of her head. If these are all normal, it will probably just take more time for her fontanel to close and her hair to grow in fully. If these show any problem, your baby should get medical help for her condition.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.