is not very common in children, but it can occur and there are several possible causes.
Perhaps the most common cause of hair loss is something called traction alopecia. This refers to the fact that a child's hair is more delicate than an adult's hair, and tugging or pulling on the hair roots can cause them to come loose. Traction alopecia is especially common with too frequent brushing or combing or with hairstyles that put a lot of stress on the hair, such as tight braids or pony tails.
Telogen effluvium is another form of generalized hair loss which leads to thinning of the hair on the head following a stress or illness
(such as a bad infection). The stress causes temporary disruption of the normal growth cycle of the hair, and leads to shedding of hair for several months. Telogen effluvium usually gets better on its own and is usually not severe enough to cause bald spots.
Other causes of hair loss in children, such as fungal infections and autoimmune reactions causing hair loss (alopecia areata), are less likely as these usually lead to bald patches, which your daughter does not have.
If the problem persists, you should talk to your daughter's pediatrician