CMV Infection During Pregnancy
Cytomegalovirus (CMV) is a common virus, but during pregnancy, it can cause anxiety — especially when blood tests show a positive IgG or IgM. In Sri Lanka, many pregnant women undergo TORCH testing, but few understand what the results really mean or what to do next.
If your report says CMV IgM positive, IgG positive, or both — don’t panic. Here’s what you need to know about CMV during pregnancy, and when to consult a virologist in Sri Lanka.
What Is CMV and Why Is It Important in Pregnancy?
CMV (cytomegalovirus) is a herpes family virus. It spreads through:
- Saliva
- Urine (e.g., from young children)
- Close contact or sexual transmission
Most CMV infections in healthy adults are mild or asymptomatic.
However, in pregnancy, a primary infection (first-time exposure) can sometimes:
- Cross the placenta
- Infect the unborn baby (congenital CMV)
- Cause long-term effects (hearing loss, growth restriction, neurodevelopmental delays)
Understanding CMV IgG and IgM Results
| Test | What It Means |
|---|---|
| IgG Positive, IgM Negative | Past infection — usually safe |
| IgG Negative, IgM Positive | Possible recent infection — may need further testing |
| Both IgG & IgM Positive | Could be recent infection or reactivation — needs expert interpretation |
| Both Negative | No past infection — susceptible if exposed |
Note: A positive IgM does not always mean active infection. It may persist for months or appear during reactivation.
Do I Need an Avidity Test?
If both IgG and IgM are positive, you may be offered a CMV IgG avidity test. This tells whether the infection happened:
- Recently (low avidity) → higher risk to baby
- In the past (high avidity) → lower or no risk
How Does CMV Affect the Baby?
Most CMV infections in pregnancy do not harm the baby. However, in congenital CMV, possible effects include:
- Low birth weight
- Jaundice or enlarged liver/spleen
- Hearing loss (may appear later)
- Seizures or developmental delays
CMV is one of the leading causes of non-genetic hearing loss in newborns worldwide.
What to Do If Your CMV Test Is Positive
Step 1: Don’t panic — CMV is common, and most babies are born healthy
Step 2: Confirm the type of infection (primary vs past vs reactivation)
Step 3: Get guidance from a clinical virologist
Step 4: In rare high-risk cases, further testing (e.g., fetal ultrasound or PCR of amniotic fluid) may be advised
Virology.lk can connect you with experts to interpret your results and recommend the safest plan forward.
Can I Prevent CMV in Pregnancy?
Yes — especially if you work with children (teachers, day-care workers, mothers of toddlers):
- Wash hands frequently, especially after diaper changes or wiping noses
- Avoid sharing utensils or food with young children
- Practice safe hygiene with bodily fluids
There's currently no vaccine for CMV, but hygiene measures are effective.