Nieman: Awareness is needed about the harmful virus that is transmitted from mother to baby

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When a woman is pregnant, we use the term “she is expecting.” This, of course, means that she hopes to have a healthy baby, ideally born full term, without complications, and then most women hope to breastfeed a healthy baby.

Not long ago I met a couple who were indeed expecting the above and everything went well until the baby failed the newborn hearing test. Suddenly, his expectations went from normal to fear; from hope to despair. Even as I listened to them describe her abrupt turn onto an unexpected trajectory, I felt compassion when her mother burst into tears as she shared the family’s story.

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Upon further investigation, it was determined that the cause of the deafness was due to an infection called cytomegalovirus (CMV). When a baby becomes infected through the mother during pregnancy, it is called congenital CMV. The latter is responsible for 20 percent of all deafness diagnosed during the neonatal period.

CMV is the most common infection passed from pregnant women to babies. It belongs to a family of viruses known as the herpes tribe (of course, in this family the most notable are genital herpes and cold sores. But the herpes family is also made up of mononucleosis and chickenpox). These viruses live forever in the body and become dormant, dormant, only to burst out under certain circumstances.

More than half of adults have been infected with CMV before the age of 40, but most do not know they have been infected. It is transmitted through blood, saliva, breast milk, tears, urine, semen and vaginal fluids.

People who work in daycare centers and those who have close contact with babies as health care providers are at higher risk of contracting CMV.

Saliva is easily shared by licking a pacifier to “clean” it after it falls on a surface, or by sharing toothbrushes, foods, drinks, cups, straws, or forks. These habits should be discouraged. As expected, washing your hands after coming into contact with secretions greatly reduces the risk of infection.

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If an expectant mother becomes infected with CMV during pregnancy, she will transmit it to her baby in about 33 percent of cases. If she was infected with CMV before becoming pregnant, then the risk of transmitting it is about one percent.

Not all babies infected with CMV through the mother during pregnancy have symptoms at birth. If a baby becomes infected and goes undetected, bad things can happen later; Bad enough to traumatize parents and cost our healthcare system millions of dollars.

You might think that if 0.6 to 1.2 percent of newborns had been infected with CMV, our health care system would routinely test babies’ urine during the first three weeks of life. But that’s not uniformly the case in Canada. In Saskatchewan and some other provinces, babies are tested, but in Alberta that’s not the case… yet.

Those who advocate early detection aim to change the current situation and move from gradual screening to universal screening. (An excellent Canadian resource on CMV, and specifically congenital CMV, is and in the US

Undiagnosed congenital CMV can cause intellectual and developmental disabilities, smaller than expected head sizes, seizures, vision loss, poor growth, problems with the liver and spleen, pneumonia, and purple spots on the skin. The subsequent rash looks like a blueberry muffin. These problems can require numerous specialists as layers and layers of problems develop. Congenital CMV is the second cause of intellectual disability after Down’s Syndrome. About 25 percent of hearing loss diagnosed by age four is due to CMV.

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Ideally, early detection and early treatment can prevent later pathology and distress for parents who were unaware of the broad impact that congenital CMV can have on what appeared to be a healthy baby at birth. Antiviral medication before six months remains the gold standard, because the sooner it is treated after detection, the better the outcome.

General knowledge about CMV during pregnancy among doctors and the public remains low, and for that reason, I recommend visiting or contacting CEO Kayla McNally ([email protected]).

I recently learned that research conducted at the University of Calgary also includes input from parents of babies with congenital CMV. Who better to provide information to a team working on solutions than parents who experienced it firsthand?

Dr. Nieman is a community pediatrician and founder of Center 70 Pediatrics. He has written monthly columns for the Herald since 1999. For more information, see

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