CMV (Cytomegalovirus) Infection Risk in Pregnancy
The short answer
CMV is the most common congenital infection, affecting about 1 in 200 babies. Many adults already have CMV antibodies. Primary (first-time) CMV infection during pregnancy carries the highest risk to the baby. Prevention centers on frequent hand washing, especially after contact with young children's saliva, urine, and other body fluids.
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By Age
What to expect by age
CMV infection in the first trimester carries the highest risk of serious effects on the baby. If you work with young children or have a toddler, practice excellent hand hygiene: wash hands after changing diapers, wiping noses, or handling toys that have been mouthed. Do not share utensils, cups, or food with young children. Do not kiss young children on the mouth.
Continue preventive measures throughout pregnancy. CMV transmission can occur at any stage. If you develop a mono-like illness (prolonged fever, fatigue, swollen glands), tell your provider. CMV testing can determine if you have a recent infection. Most babies exposed to CMV in utero are born healthy.
CMV infection later in pregnancy has a higher transmission rate but typically less severe effects on the baby. If diagnosed with CMV during pregnancy, your provider will discuss monitoring options including detailed ultrasound and, in some cases, amniocentesis. New antiviral treatments are being studied.
What Should You Do?
When to take action
- Practicing good hand hygiene with young children
- Having positive CMV antibodies from a past infection (indicating immunity)
- You work in a daycare or frequently care for young children
- You developed prolonged flu-like symptoms during pregnancy
- You want to be tested for CMV immunity
- You have been diagnosed with primary CMV infection during pregnancy and need specialist referral
- Ultrasound shows findings concerning for congenital CMV
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
Related Maternal Concerns
Parvovirus B19 (Fifth Disease) in Pregnancy
Fifth disease (caused by Parvovirus B19) is usually mild in adults but can pose risks during pregnancy, including fetal anemia and hydrops fetalis in rare cases. About 50-60% of adults are already immune from childhood exposure. If you are exposed during pregnancy, blood testing can determine your immunity status and guide monitoring.
Varicella (Chicken Pox) Exposure While Pregnant
Varicella (chickenpox) during pregnancy can cause complications for both parent and baby, including varicella pneumonia in the parent and congenital varicella syndrome in the baby (rare, mostly with first/second trimester infection). Most adults are immune through vaccination or previous infection. If you are exposed and unsure of your immunity, contact your provider immediately for testing.
Dealing with Abnormal Prenatal Screening Results
An abnormal prenatal screening result can be terrifying, but it is important to understand that screening tests are designed to cast a wide net and have significant false-positive rates. Most people with abnormal screening results go on to have healthy babies after further testing confirms the baby is fine. An abnormal screening is a reason for more information, not a diagnosis.
Pregnancy Over 35 (Advanced Maternal Age)
While pregnancy after 35 carries some increased risks (including chromosomal abnormalities, gestational diabetes, and hypertension), the vast majority of people over 35 have healthy pregnancies and healthy babies. The term "geriatric pregnancy" is outdated and does not reflect reality. With appropriate prenatal care and monitoring, outcomes are excellent.
Amniocentesis Questions and Fears
Amniocentesis is a diagnostic test performed between 15-20 weeks that analyzes amniotic fluid to detect chromosomal conditions and genetic disorders with over 99% accuracy. The risk of pregnancy loss from the procedure is approximately 1 in 500-1,000 when performed by an experienced provider. Understanding the actual risks can help you make an informed decision.
20-Week Anatomy Scan Unexpected Findings
The 20-week anatomy scan checks your baby's major organs, structures, and growth. Most scans are completely normal. When unexpected findings are identified, they range from minor variants that resolve on their own to conditions that need further evaluation. Many findings require nothing more than a follow-up ultrasound to confirm the baby is developing well.