CMV Pregnancy Prevention: Testing And Treatment

CMV pregnancy prevention now has clear testing and treatment pathways. Cytomegalovirus is the most common infection passed from mother to baby during pregnancy and is a preventable cause of childhood disability. Around one in 200 babies is born with congenital CMV, which can result in microcephaly, hearing loss, developmental delay, and cerebral palsy, yet many women remain unaware of the risk.

Testing and education can significantly reduce infection risk

Identifying women who have never had CMV and remain susceptible is key. Early testing and targeted education for these CMV-negative women has been shown to reduce infection rates from 7.6% to 1.6%. This powerful reduction means only 17 at-risk pregnant women need to be given this information to prevent one CMV infection during pregnancy. Targeted testing may apply to close to half of pregnant Australians.

Hayley Smithers-Sheedy highlighted the impact, stating: "Early testing and targeted education for CMV-negative women have been shown to reduce infection rates from 7.6% to 1.6%." Lisa Hui reinforced the efficiency, saying, "Only 17 at-risk pregnant women need to be given this information to prevent one CMV infection during pregnancy."

How CMV spreads and how to reduce exposure

The virus spreads through direct contact with body fluids, particularly saliva, nasal mucus, and urine of young children. Young children can shed high levels of CMV for long periods while remaining well. Parents, carers, and childcare workers are therefore at increased risk.

Every pregnant woman should receive information on simple hygiene precautions to reduce CMV infection risk, especially in the first trimester. These precautions include washing hands after changing nappies or wiping young children’s noses, kissing young children on the forehead rather than the mouth, and avoiding sharing food, drinks, or utensils with young children.

New treatment options offer protection after early infection

Until recently, routine CMV blood testing in pregnancy was not recommended because there was no proven treatment to reduce transmission to the developing baby. Evidence now shows that if a woman has a primary, or first-time, infection in early pregnancy, prompt treatment with the antiviral drug valaciclovir can reduce the risk of CMV passing to the fetus.

A 2020 randomised trial provided the breakthrough data. It found that among women who had a primary infection in the first trimester, CMV transmission to the fetus occurred in 48% of those given a placebo, compared with only 11% of those treated with valaciclovir.

Valacyclovir is now being offered to women with first-trimester CMV infection to reduce fetal infection risk. Treatment should ideally begin within six weeks of infection and by 14 weeks of pregnancy. Specialist oversight and regular blood tests are needed due to potential side effects for the mother, including kidney impairment, low white cell count, and anemia. In Australia, this high-dose valaciclovir treatment is currently available off-label.

Guidelines now recommend awareness and targeted testing

Australian guidelines now recommend all pregnant women be given information about CMV, the potential risk to their baby, and simple hygiene precautions. They also advise early CMV testing for women at increased risk of exposure, including those who work with or care for young children.

In 2024, a group of European expert clinicians recommended testing all women for CMV. Several countries have begun implementing these universal testing models. However, Australian guidelines do not yet recommend universal screening due to the need for more research on cost-effectiveness, feasibility, workforce, and capacity. More research is needed to determine if Australia’s health system has the resources to implement it safely and equitably.

All pregnant women should receive information on CMV and hygiene precautions, especially in the first trimester, to reduce infection risk.