Please read this if you are pregnant

This is a medical alert!

Please read this if you are pregnant. Be aware of the devastating and underestimated effects this condition may have on your unborn child’s hearing.

This condition is cytomegalovirus (CMV) infection.

Please read this if you are pregnant.
Cytomegalovirus (CMV) is an important cause of hearing loss in newborn babies.

What is CMV?

Cytomegalovirus (CMV) is a virus which is part of the Herpesviridae family. It occurs commonly in humans. It is one of the most common pregnancy related infections in the world and can have devastating effects on a newborn baby. This infection can strike at any time during pregnancy. It may lead to numerous abnormalities in your newborn, even death.

Why is it so important to be aware of CMV?

CMV is the most common cause of non-genetic childhood sensorineural hearing loss in the world. It is the second most common cause of single sided deafness (SSD) in newborn babies and young children in the world.

The worldwide prevalence is around 0.64% of newborn babies but in isolated studies in South Africa between 2.9% and 5.95%. This is really concerning. There is even reported prevalence numbers as high as 14% in some areas in China.

If the statistics of newborn babies in South Africa in 2018 indicate 1 009 065 newborns it means that between 30 000 and 60 000 babies would have been infected with CMV. In comparison, Down Syndrome occurred between 1300 and 2100 babies.

CMV is a major cause of neurodevelopmental delay and more common than is realized.

What is the relationship of CMV and hearing loss?

Of all newborn babies with congenital CMV only 10% will be symptomatic and have other signs of CMV. Of these babies, 33% will go on to develop hearing loss.

The problem is the 90% of newborns infected with CMV will be asymptomatic at birth. Some may be asymptomatic but with only hearing loss, picked up with neonatal hearing screening. Of the asymptomatic babies, 10% will develop hearing loss, 5% will require hearing amplification and rehabilitation and 2% will eventually require cochlear implantation (CI).

So even if you have a normal baby at birth, it may still be infected with CMV which can cause later onset hearing loss!

In the US, 15%-20% of all cases of bilateral moderate to profound sensorineural hearing loss (SNHL) among young children is attributable to CMV.

Hearing loss may be delayed in onset. It may  fluctuate and be progressive. Late onset hearing loss in the other/better hear can occur in 75% of patients up to 18 years of age, therefor long-term follow-up of hearing is very important.

Neonatal CMV screening

In South Africa neonatal hearing screening is advocated and practiced in many hospitals. Unfortunately, this is not true for CMV screening. This is not performed, even in some of the high risk babies.

Targeted CMV screening implies the screening of high-risk babies such as babies with complications, babies in the neonatal ICU and babies that fail their newborn hearing screening. Targeted CMV screening is performed in numerous institutions in the world and have been shown to be cost-effective.

Universal CMV screening implies the screening of every baby. It has been shown in a recent study from the US that even universal screening may be cost effective. It has now been implemented as standard practice in Ontario, Canada.

How do I test for CMV in my baby?

CMV testing can be performed on sputum, blood, and urine. The preferred method of screening is a sputum swab test, performed before breast feeding within the first 3 weeks of life. This is not a painful test. If performed after breast feeding a false positive test may occur due to CMV in the mother’s breast milk. Testing after 3 weeks is too late as by this time the baby could have acquired it post-natal/after birth and be likely to mount an immune response against it.

What happens if the screening CMV test is positive?

If the sputum screening test is positive, it would usually be confirmed with a blood test. If then diagnosed with CMV the neonatologist/paediatrician will discuss the possibility of anti-viral treatment with the mother. This may prevent late onset hearing loss. It would also mean the need of long term follow up for the development of hearing loss.

How should hearing be followed up in babies with CMV?

Hearing should be tested in asymptomatic babies at least every 6 months for the first 3 years and thereafter every year until 18 years. The reason for this is that late onset hearing loss can occur.

What can be done for hearing loss due to CMV?

Hearing loss due to CMV is managed with hearing aids but in some patients with severe or profound hearing loss, CI may be the only option. New data supports the treatment of single sided deafness (SSD) with CI, even in children.

 How can I avoid contracting CMV?

Unfortunately, a vaccine is not yet available. There are nevertheless a few important steps that can minimize the risk of contracting CMV in pregnancy. For a nice overview please visit The National CMV Foundation at:

Reference list of articles

  1. Nance WE, Lim BG, Dodson KM. Importance of congenitalcytomegalovirus infections as a cause for pre-lingual hearingloss. J Clin Virol. 2006;35:221-225.
  3. Barbi M, Binda S, Caroppo S, Ambrosetti U, Corbetta C, Sergi P. A wider role for congenital cytomegalovirus infection in sensorineural hearing loss. Pediatr Infect Dis J 2003 Jan;22(1):39-42
  4. Kenneson A, Cannon MJ. Review and meta-analysis of the epidemiology of congenital cytomegalovirus (CMV) infection. Rev Med Virol 2007;17:253–76.
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  14. Rawlinson WD, Boppana SB, Fowler KB, et al. Congenita cytomegalovirus infection in pregnancy and the neonate: consensus recommendations for prevention, diagnosis, and therapy. Lancet Infect Dis. 2017;17:e177-e188.
  15. Lanzieri TM, Chung W, Leung et al. Hearing Trajectory in Children with Congenital Cytomegalovirus. Otolaryngology-Head and Neck Surgery 2018;158(4) 736-744
  16. Rawlinson WD, Palasanthiran P, Hall B, et al. Neonates with congenital cytomegalovirus and hearing loss identified via the universal newborn hearing screening program. J Clin Virol 2018;102:110-115.
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