Pregnancy infections linked to congenital hearing impairment

According to the World Health Organisation, more than five per cent of the world’s population (430 million people) live with disabling hearing loss.  Any person who is not able to hear as well as someone with normal hearing (hearing thresholds of 20 decibels (dB) or better in both ears) is said to have hearing loss. 

Nearly 80 per cent of people with disabling hearing loss live in low and middle-income countries. The prevalence of hearing loss increases with age, worsening from age 60 and above.  Hearing loss may be mild, moderate, severe, or profound. It can affect one or both ears, and leads to difficulty in hearing conversational speech or loud sounds. 

People with severe hearing loss are normally referred to as deaf. Most have profound hearing loss, which implies very little or no hearing and can benefit from hearing aids, cochlear implants, and other assistive devices.  

Causes

When Rhoda Mpiirwe had her first child, she could tell something was wrong with him. At three months old, her son could not respond to any sounds. “Sometimes when a child cries and the mother calls them, they stop a bit and follow the voice, but mine could not do that,” she says.

By five months, it started dawning on Mpiirwe that her child could be deaf. “But she did not seek any medical attention and at nine years of age, he is deaf,” she reveals.  When she gave birth to her second child nine years later, she could still see the same signs at three months. After learning from her earlier mistake, Mpiirwe decided to take her daughter to a medical centre for professional help. 

According to Dr Josephine Buteru, a consultant audiologist at Let the Children Hear in Kisenyi, a Kampala suburb, who did an assessment on Mpiirwe’s second child, the defect might have been a side effect of a Rubella infection during her first pregnancy. 

Mpiirwe was not aware that she had contracted Rubella at any time during her pregnancy although she recalls noticing a rash, which she thought was pregnancy-related. Dr Buteru notes that the congenital defect would have been prevented had Mpiirwe got a Rubella vaccine during the first pregnancy. 

About acquired hearing

According to health experts, if there is no family history of deafness, congenital deafness can be caused by maternal diseases during pregnancy such as rubella and syphilis or perinatal conditions such as jaundice, anoxia (an absence of oxygen), and trauma, among others. 

Rubella

According to Dr Clemence Bitanihirwe, a speech and language therapist, if a mother did not get proper measles treatment as a child, she is at a high risk of getting Rubella during pregnancy which is dangerous to the baby. Taking a Rubella vaccine could, therefore, help mothers avoid such shortcomings. When a mother is pregnant, there are chances she might directly or indirectly affect the child’s auditory system.

It is suspected that prenatal exposure to environmental toxins or recreational drugs may result either directly or indirectly in the underdevelopment of auditory abilities. 

Maternal tobacco smoking elevates the risk of cognitive and auditory processing deficits. The use of cocaine by pregnant women may lead to neonatal retro cochlear hearing loss and abnormalities in central auditory processing. 

Prenatal alcohol exposure can give rise to Fetal Alcohol Syndrome (FAS); due to the cranio-facial anomalies associated with FAS, these individuals are prone to recurrent middle ear infections and/or fluid collection behind the eardrum, and conductive hearing loss. 

Genetic hearing loss

According to Dr Bitanihirwe, when a woman with congenital factor has a child with a man with the same congenital factor, it is possible that the couple may give birth to a hearing impaired child.

Dr Bitanihirwe, says when a new-born is not startled when one bangs on a door, constant monitoring is necessary up to about six months. At that level, it is an evident warning sign that the baby needs screening.

According to Dr Phiona Kamya, an audiologist at Kampala Audiology and Speech Centre, screening helps in ensuring that someone is not predisposed and they do or do not actually have the complication.

“At one year, if a child is not able to bubble a word or something like dadadadada, mammamama, gagagaga, it is an indication that they may not be able to speak,” Dr Bitanihirwe says. 

She adds that when a child is above two years and their voice is still not clear, or maybe the child has a tendency to increase TV volume when everyone else is comfortable, or wants to sit closer to the screen, then their hearing level might not be normal.  

Risk factors

Dr Kamya reveals that some hearing loss occurs at birth due to poor handling of the baby by inexperienced midwives at delivery. She adds that motor accidents, especially to boda boda riders and passengers who ride without helmets can cause secondary hearing loss that could happen at any age. 

She also states that loss of hearing can occur because of old age or exposure to noise over a long period of time, noting that employees who are exposed to very loud machinery without ear protection are also especially susceptible to hearing loss.

Dr Abubaker Bugembe, an Ear, Nose and Throat surgeon, says cerebral malaria and meningitis can cause hearing impairment in children who were not born deaf.

Other factors that may lead to hearing impairment include; aging, drugs such as the antibiotic gentamicin, sildenafil (Viagra) and certain chemotherapy drugs.  

Hearing aids

Using hearing aids can help in circumstances of partial hearing loss or reduced hearing.

According to Dr Abubaker Bugembe, an Ear, Nose and Throat surgeon, getting cochlear implants is a viable option but can be very expensive. 

“Getting cochlear implants is not a cheap venture and even after the operation, one has to go through speech and language, finding tune for the hearing aid, getting used and responding to the monotone of the implant,” he says.

Dr Kamya adds that the best time to do this is when the child is below three years when the brain is able to contain the speech. This is because as the child grows, so does the brain, adapting to the environment around and it may be hard to instill speech into the child when they are older.