Patient education: Cytomegalovirus infection and pregnancy (Beyond the Basics)

CYTOMEGALOVIRUS INFECTION OVERVIEW — Cytomegalovirus (CMV) is a virus that is transmitted by close contact with an infectious person's saliva, urine, or other body fluids. Being infected with CMV causes few or no problems in people with a healthy immune system. However, the virus can cause serious problems for infants born to people who are infected with CMV during pregnancy. When a person gets CMV infection while they are pregnant, this is called "maternal" CMV.

Primary CMV infection — The first time someone gets CMV, it is called a "primary" infection. Once a person is infected, the virus remains in their body for life, but rarely causes future problems. Most people of childbearing age have already had a CMV infection [1].

Nonprimary CMV infection — It is possible to have a CMV infection more than once. When a person has active CMV infection again, it is called a "nonprimary infection." This can happen in two ways:

●Reinfection – This is when a person contracts a new strain of the virus from another person.

●Reactivation – This is when the previous infection in the body becomes active again.

CMV SYMPTOMS — Most people who are infected with CMV have no symptoms at all. Some can have a mild flu-like illness. Symptoms may include fever; nasal congestion; sore throat, muscles, or joints; headache; and/or fatigue. The virus rarely causes serious health problems in healthy adults or children.

MATERNAL CMV DIAGNOSIS — Your health care provider can order a blood test to see if you have had CMV. The blood test also can estimate whether you have a new recent infection or were infected in the past.

CMV TRANSMISSION AND RISK TO THE BABY — If you get CMV infection while you are pregnant, the virus can cross through the placenta and infect your baby. This is called congenital CMV. Congenital infection may cause health problems for the baby.

Chance of CMV infection of the baby before birth — The chance of the virus passing to your baby before birth depends on (i) whether your infection is primary or nonprimary and (ii) how far along you are in pregnancy when the infection occurs.

Chance of complications if the baby is infected before birth — The chance of complications in the baby depends on how far along you are in pregnancy when your infection occurs.

●If a primary maternal infection occurs during the first 14 weeks of pregnancy, there is a 4 in 10 (40 percent) chance that the virus will pass to the baby (see 'Primary CMV infection' above). Of the babies who do get infected, three-quarters will be healthy, and one-quarter will have health complications. Thus, the overall chance of having a baby with CMV complications after a maternal primary infection before 14 weeks of pregnancy is about 1 in 10.

If health complications of congenital CMV occur, they include low birth weight, abnormal blood tests, or hearing loss at birth. Health complications in early childhood can include poor growth, hearing loss, vision problems, seizures, developmental delay, intellectual disability, and cerebral palsy.

●If a primary maternal infection occurs after 14 weeks of pregnancy, there is a 6 in 10 (60 percent) chance the virus will pass to the baby (see 'Primary CMV infection' above). However, the chance of health complications is much less than when the mother is infected earlier in pregnancy. The overall chance of having a baby with CMV complications is less than 1 in 100.

●If a nonprimary maternal infection occurs in pregnancy, there is only a 1 in 100 chance that the virus will pass to the baby (see 'Nonprimary CMV infection' above). The chance of health complications depends on when the baby is infected, as described above, but this timing can be difficult to determine with nonprimary maternal infection.

Preventing mother-to-baby transmission — Doctors are testing different medications that may reduce the risk of passing CMV infection to your unborn baby. An antiviral medication called valacyclovir (brand name: Valtrex) may help to reduce this risk if taken before 14 weeks of pregnancy, but is still being studied. Your doctor can talk to you about the possible risks and benefits of taking this medication for both the baby and you.

Any treatment should only be prescribed by a specialist with expertise in infectious diseases and pregnancy. It is important to make sure you understand the potential risks and benefits before beginning any treatment.

Congenital CMV diagnosis before birth — The most accurate way to tell if the virus has passed to your baby before birth is to have a medical procedure called an "amniocentesis." This test is usually done at least 8 weeks after you become infected, commonly around 20 weeks of gestation [2]. During an amniocentesis, a needle is passed through the skin of your abdomen and into your uterus to collect a small sample of fluid from around the baby. The fluid is then tested for the CMV virus. A "CMV positive" result means the baby has congenital CMV infection. A "CMV negative" result means the baby has not been infected.

Predicting health outcomes for your child — If the amniocentesis shows that your baby does have congenital CMV infection, you will be offered regular ultrasounds to check your baby's growth and brain development. Your specialist may also discuss a fetal brain magnetic resonance imaging (MRI) scan to check your baby's brain development. If there are changes on the ultrasounds and/or MRI scans that indicate that your baby has been affected by CMV, then your doctor will explain these findings to you.

If all the imaging tests are normal, the chance of your baby having major health problems after birth is reduced. However, some babies still have complications, including hearing loss or developmental delay, even if the ultrasounds and MRI are normal. The role of medical therapies to treat congenital CMV infection before birth is still evolving. Your doctor will discuss your options with you.

CMV diagnosis after birth — If you have had CMV infection during pregnancy, you will be offered testing of the baby for CMV at the time of birth, whether or not you had an amniocentesis. This can involve testing the placenta as well as your newborn baby's urine or saliva.

If your baby is confirmed to have CMV infection, you will have the option of seeing a pediatrician to discuss follow-up and possible treatments. Ongoing testing for hearing, eye checks, and medical follow-up of your baby will be recommended.

Breastfeeding — If you have a CMV infection during pregnancy and your baby does not get it before birth, they may become infected through your breast milk. However, breastfeeding is still encouraged if your baby is healthy as CMV acquired after birth rarely causes problems in healthy full-term babies. If you plan to breastfeed or have questions, talk to your doctor, nurse, or midwife.

PREVENTING CYTOMEGALOVIRUS INFECTION — The risk of becoming infected with CMV is higher for pregnant people who live with young children or work in day care centers. This is because young children are infectious for longer time after a CMV infection compared with adults.

Good hygiene practices, especially hand washing, can decrease the chances of developing CMV infection during pregnancy. Guidelines from the Centers for Disease Control and Prevention (CDC) are available and include the following:

●Wash your hands with soap and water after changing diapers

●Avoid getting a child's saliva in your mouth by, for example, not sharing food, eating utensils, or cups with a child

These cannot eliminate your risk of getting CMV, but may lessen the chances of getting it.

Vaccines against CMV are also being tested but are not yet available.

WHERE CAN I GET MORE SUPPORT? — It can be worrying to be told that your baby may have congenital CMV, so it is important that you have support during this stressful time. This might be your partner, relative or friend; midwife or doctor; your baby's pediatrician; and/or a mental health professional.

Most importantly, you are not alone. Tell your doctor or midwife if you need more support. There are also many national CMV community groups that support pregnant people and families in this situation. It can help to talk with other people who are going through something similar.

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Cytomegalovirus (The Basics)
Patient education: Avoiding infections in pregnancy (The Basics)
Patient education: How to plan and prepare for a healthy pregnancy (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Avoiding infections in pregnancy (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Cytomegalovirus infection in pregnancy
Congenital cytomegalovirus infection: Clinical features and diagnosis
Epidemiology, clinical manifestations, and treatment of cytomegalovirus infection in immunocompetent adults
Approach to the diagnosis of cytomegalovirus infection
Overview of diagnostic tests for cytomegalovirus infection

The following organizations also provide reliable health information.

●National Library of Medicine

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●Centers for Disease Control and Prevention (CDC)

●Infectious Diseases Society of America

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