In brief — the direct answer
Some infections can pass from mother to fetus and affect pregnancy. Maternal infection, fetal infection and fetal effects are different questions. Assessment uses the suspected organism, timing, appropriate laboratory testing and imaging. Treatment and follow-up depend on the diagnosis and current specialist guidance; there is no single antiviral pathway for all congenital infections.
What is Fetal Infections (CMV & Toxoplasmosis)?
- Cytomegalovirus (CMV): A common virus that usually spreads through contact with the saliva or urine of young children. If a mother gets CMV for the first time during pregnancy (primary infection), there is a 30-40% chance of transmission to the baby.
- Toxoplasmosis: Caused by a parasite found in undercooked meat, unwashed soil, or cat litter.
Both infections can affect the baby's developing brain, eyes, and hearing. The risk of severe issues is highest if the infection occurs in the first trimester, while the risk of transmission is highest in the third trimester.
Who is at risk?
You may be at higher risk for these infections if:
- CMV: You work with young children (teachers, daycare workers) or have toddlers at home.
- Toxoplasmosis: You handle raw meat frequently, garden without gloves, or have close contact with cats and their litter boxes.
Standard blood tests at the beginning of pregnancy check for 'antibodies' (IgG and IgM) to see if you have had these infections in the past (which provides protection) or if you have a new infection.
How we diagnose it
Diagnosis involves a two-step process:
- Maternal Testing: Blood tests to confirm a 'primary' or 'recent' infection in the mother.
- Fetal Testing: If the mother is infected, we perform an Amniocentesis (usually after 20-21 weeks) to test the amniotic fluid for the virus's DNA using a PCR test. This is the only way to know for sure if the baby has been infected.
- Ultrasound Surveillance: We look for 'soft markers' like brain calcifications, ventriculomegaly (enlarged fluid spaces), echogenic bowel (bright bowel), or slow growth.
What does management involve?
Treatment depends on the organism, timing of maternal infection, fetal testing and the guideline followed. Selected recent primary CMV infections may be considered for specialist-prescribed valaciclovir under an appropriate protocol, with counselling about evidence, licensing and maternal renal monitoring. It is not a universal treatment for every positive CMV antibody result or proven fetal infection. Toxoplasmosis needs organism-specific treatment selected for gestation and fetal findings. Do not self-start antivirals or antibiotics; ultrasound, laboratory and neonatal follow-up may all be needed.
What are the outcomes?
The outlook depends on the infection, timing and whether the fetus is infected or affected. A positive maternal antibody test alone does not establish fetal infection or damage. Correctly timed amniotic-fluid PCR can help diagnose selected infections but has timing and test limitations. Reassuring prenatal imaging does not exclude later hearing or developmental effects in congenital CMV. Confirm the neonatal testing and follow-up plan.
When to see a subspecialist
If your blood tests show a 'recent CMV infection' or 'positive Toxoplasmosis IgM,' or if a scan shows 'bright spots in the brain or belly,' you should be seen by an MFM consultant immediately.
Our team provides the specialized counseling required to understand the difference between 'maternal infection' and 'fetal disease.' We facilitate the amniocentesis PCR testing and provide access to the latest antiviral protocols to give your baby the best possible protection.