In the genes
50% of all cases of congenital hearing loss in children are caused by genetic factors.
An inherited hearing loss does not necessarily mean that one or both parents also are hard-of-hearing. In fact, about 90 % of children with congenital hearing loss are born to hearing parents, who may have passed on the condition by being carriers of recessive genes. In 20-30% of cases, the cause of congenital hearing loss is not known.
Prenatal illnesses account for 5-10% of the cases of congenital hearing loss and include infections during pregnancy, such as rubella, cytomegalovirus, herpes or syphilis, toxins consumed by the mother during pregnancy or other conditions occurring at the time of birth or shortly thereafter. Babies born prematurely also have an increased risk of becoming hard-of-hearing.
Prenatal causes make up 5-15%.
After birth, traumas to the head or childhood infections, such as meningitis, measles or chicken pox, can cause permanent hearing loss. Certain medications, such as the antibiotic streptomycin and related drugs, also can be the cause of the child's hearing problems.
Ear infections like Otitis Media may cause temporary hearing loss or lead to a permanent hearing impairment if left untreated.
10-20% of hearing loss occurrences are due to postnatal causes.
Hearing loss in infancy can be difficult to recognize. In almost two thirds of cases, parents are the first to suspect hearing loss, with other health care providers suspecting it first in approximately 15% of cases, and pediatricians in roughly 10%.
Early hearing screening as well as paying attention to the child's responses and general behaviour is therefore important for starting treatment as early as possible. Children as young as age 4 weeks can benefit from a hearing aid.
Sources: www.marchofdimes.com , and www.emedicine.com