A CMV pregnancy will not usually be defined as a “high risk pregnancy” and the course of the delivery is no different than that of any other delivery, but the team will be updated regarding an infection or suspicion for CMV infection.
It is important to know that in the event of a birth following a CMV pregnancy, there is an organized protocol of tests recommended by experts on the subject, which need to be performed during the stay in the neonatal department.
Under the tab Protocols – Diagnosis, Treatment and Follow-Up you can read about the protocols that were given to us from the different hospitals. It is the responsibility of the mother to verify before the birth that the protocol is relevant.
The importance of performing the test in maximum proximity to the time of the birth stems primarily from the need to start treating the baby if the tests discover findings that can testify that the baby is symptomatic.
In addition, performing the tests during the stay in the neonatal department saves much bureaucracy involved in making appointments, receiving Form 17s and arriving at the hospital several times over the first weeks of the baby’s life.
The tests that confirm whether the baby has congenital CMV:
Saliva test – performed in some hospitals and provides a reliable answer only if negative, indicating that the fetus was not infected. Its advantage is the simplicity of sample collection.
A positive result, indicating infection, may also result from passage through the birth canal or breastfeeding, and therefore is not definitive. If the saliva test is positive, a urine test must also be performed.
Urine test – provides a reliable and definitive answer regarding whether the baby was infected during pregnancy. Results are usually available within a few days of sample collection. However, unlike the saliva test, there can sometimes be technical difficulty in collecting a urine sample from a newborn.
Urine test results:
Negative – indicates the baby was not infected. This concludes the story of a pregnancy with CMV, and there is no further concern about the virus. After birth, the baby is like any other infant, and postnatal infection is not expected to have long-term consequences.
Positive – indicates the baby was infected during pregnancy.
It is crucial to perform these tests within the first three weeks of life. After this period, it is generally not possible to determine with certainty whether the infection was intrauterine or occurred during birth or afterward.
Another option for diagnosing congenital CMV if the first three-week window was missed is the Guthrie paper test (routine newborn blood spot test collected in the first days of life). This method is limited and is only accurate if positive. A negative result on the Guthrie paper test does not rule out congenital CMV.
If the urine test is positive, several additional tests are performed after birth:
Blood tests – complete blood count and kidney and liver function.
Brain ultrasound – performed by a pediatric radiologist.
Eye exam – performed by an ophthalmologist to rule out findings consistent with congenital infection.
Bera hearing test (ABR) – evaluates the brainstem response to sound stimuli. More information on this test can be found in the Q&A tab.
Postnatal test results and follow-up
If all targeted scans during pregnancy were normal, both brain ultrasound and postnatal eye exams are expected to be normal.
There is still a risk of hearing problems, which cannot be detected through prenatal imaging.
Normal test results –
If postnatal tests are normal, the baby is defined as asymptomatic and is expected to have normal neurological development.
However, even an asymptomatic baby may develop hearing impairment in 5–7% of cases. Therefore, children infected with CMV in utero will continue follow-up with a pediatric infectious disease specialist and hearing monitoring during the first years of life. In most hospitals, follow-up is every six months until around age five.
In some hospitals, follow-up in the first year also includes neurology and ophthalmology. Differences in hospital follow-up protocols can be found in the “Protocols – Diagnosis, Treatment, and Follow-up” tab.
