Around 1 out of 200 babies are born with Congenital Cytomegalovirus (Congenital CMV), making it the most common infectious cause of birth defects in the US, according to the CDC.

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1 in 5 babies with congenital CMV will suffer from long-term health problems, most commonly hearing loss, which may progress from mild to severe over the first two years of the child's life. In addition, CMV may be responsible for up to 15% of stillbirths and is associated with damage to the placenta which is dangerous to your baby.

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Despite this, over 90% of parents have never heard of CMV, which is not surprising considering that less than half of OBs report routinely educating their patients about the risks.

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The CMV virus is only harmful to pregnancy when it is active, for example:

• when you catch it for the first time (also known as a primary infection)

• if it is reactivated (called a recurrent infection) because your immune system is weakened during pregnancy, or

• if you have been infected again by a different strain of CMV (called reinfection)

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A primary infection is the most likely form of congenital CMV transmission, and you are most likely to pass CMV to your baby the later in your pregnancy you are infected. Thankfully, the risk of your baby developing serious defects as a result of CMV infection appears to be lowest in the 3rd trimester, even though transmission rates are higher.

CMV is passed like many viruses through bodily fluids. For pregnant women in particular, the most likely source of CMV infection is through the saliva or urine of a toddler, as 1 in 3 children in the US will contract CMV by the age of 5. This is especially true for mothers of small children and those who work in childcare or early education settings.

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The good news is that you can reduce your risk of CMV infection during pregnancy using the same strategies that you already know to protect yourself against the common cold, flu, and other communicable diseases:

• Don’t share food, utensils, drinks, or straws with others

• Kiss your kids on the forehead to avoid saliva and be careful handling pacifiers

• Wash your hands frequently (for example, after changing diapers, wiping a little one’s nose/mouth, or handling their toys and food)

Prenatal healthcare providers in the US do not routinely screen pregnant women or newborns for CMV, despite the fact that CMV testing is cheap and carries no risks, as it requires only a simple blood draw from the mother or saliva, urine, or blood from the newborn.

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The National CMV Foundation recommends that all pregnant-capable people learn their CMV status before they start trying to conceive. Depending on your level of risk (as determined by whether you have never had CMV, have had a recent CMV infection, or have had a past CMV infection), your doctor may recommend you take precautions to avoid CMV infection, request additional monitoring to check your baby for signs of congenital CMV infection, or agree to additional maternal CMV screening as part of your normal blood tests over the course of your pregnancy.

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If your baby has contracted CMV in utero, early detection is key, so never hesitate to ask your healthcare provider to check your status. There are promising emerging interventions during pregnancy or after birth to help monitor and treat babies who contract congenital CMV – but only if you know an infection has occurred!

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As always, we urge you to speak with your doctor about any questions or concerns you may have (see #AlwaysAsk) and advocate (don't hesitate to #UseYourMomVoice!) for whatever tests or monitoring you need to feel reassured during pregnancy. Remember, no one knows your baby or your body better than you!