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Study on Valacyclovir for Preventing and Treating Cytomegalovirus (CMV) in Pregnant Women

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effectiveness and safety of a medication called valacyclovir in pregnant women who have a primary infection with cytomegalovirus (CMV). CMV is a common virus that can cause infections, and a primary infection means it is the first time the person has been infected. The study aims to see how well valacyclovir works in preventing the virus from being passed from the mother to the baby during pregnancy and in treating the infection, depending on the dose of the drug used.

Participants in the study will be pregnant women who have recently developed CMV infection. The study will compare different doses of valacyclovir to understand which dose is most effective and safe. The medication will be given in the form of film-coated tablets, which are taken orally.

The study will follow the participants over a period of time to monitor the presence of CMV in the amniotic fluid, which surrounds the baby in the womb, and in the blood of both the mother and the fetus. The study will also look at the number of platelets, which are cells that help with blood clotting, in the fetus. Additionally, the study will track any side effects experienced by the participants. The goal is to gather information that will help in understanding how to best use valacyclovir to manage CMV infections during pregnancy.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm eligibility. This includes verifying the presence of specific antibodies to cytomegalovirus (CMV) and confirming a singleton pregnancy before 16 weeks.

    Written informed consent is required to participate in the study.

  2. Step 2

    Medication administration

    The medication used in the trial is valaciclovir, administered orally in the form of film-coated tablets known as VACICLOR 500 MG.

    The dosage and frequency of administration depend on the specific group assigned within the study. The aim is to evaluate the efficacy and safety of different doses in preventing and treating CMV infection.

  3. Step 3

    Regular monitoring

    Regular visits are scheduled to monitor the health of both the mother and the fetus. These visits assess the presence of CMV DNA in the amniotic fluid and the replication level of the virus in maternal and fetal blood.

    The platelet count in the fetus is also monitored, as well as any missed doses of the medication.

  4. Step 4

    Evaluation of outcomes

    The primary outcome is the percentage of newborns in whom CMV DNA is not detected in the amniotic fluid, assessed at specific visits.

    Secondary outcomes include the level of CMV DNA replication and the frequency of any adverse events experienced during the study.

  5. Step 5

    Completion of study

    The study is estimated to conclude by August 31, 2026. Final assessments are conducted to evaluate the overall efficacy and safety of the treatment regimen.

Who can join the trial?

6 criteria

  • Pregnant women aged 18 years and older.
  • The presence of IgG antibodies to CMV, whose previous result in the current pregnancy was negative (seroconversion). IgG antibodies are proteins in the blood that show if you have been exposed to a virus like CMV. Seroconversion means that these antibodies have appeared in your blood during this pregnancy.
  • Antibodies to CMV in the IgM and IgG classes with low avidity. IgM antibodies are another type of protein that shows recent exposure to a virus. Avidity refers to how strongly these antibodies bind to the virus, and low avidity suggests a recent infection.
  • The presence of the above-mentioned antibodies before 16 weeks of pregnancy.
  • Giving written informed consent to participate in the study. This means you agree to join the study after being fully informed about it.
  • Confirmed singleton pregnancy. This means you are pregnant with one baby, not twins or more.

Who cannot join the trial?

8 criteria

  • Individuals who are not pregnant women cannot participate.
  • Men are not eligible to join the study.
  • Participants must not have any other serious health conditions that could interfere with the study.
  • Individuals who are unable to follow the study procedures or take the study medication as directed are excluded.
  • Participants who are currently taking medications that might interact with the study drug cannot join.
  • Individuals with a known allergy to the study medication or similar drugs are not eligible.
  • Participants who have previously been treated for the same condition with the study medication are excluded.
  • Individuals who are part of another clinical trial at the same time cannot participate.
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Investigated drugs

Valacyclovir is a medication used in this clinical trial to prevent and treat intrauterine infection in pregnant women who have a primary cytomegalovirus (CMV) infection. The study aims to evaluate how effective and safe valacyclovir is in stopping the virus from being passed from the mother to the unborn baby. The trial is focused on understanding how different doses of valacyclovir might affect its ability to prevent and treat the infection.

What is already known about the treatment

Valacyclovir – Valacyclovir is administered orally in the form of tablets. It is currently being studied in clinical trials for its effectiveness and safety in preventing and treating intrauterine infections caused by primary cytomegalovirus (CMV) infection in pregnant women. The main therapeutic indication is the prevention of CMV transmission and treatment of CMV infections. At the molecular level, valacyclovir works by inhibiting viral DNA replication, which prevents the virus from multiplying. It is classified as an antiviral medication.

Investigated diseases

Primary Cytomegalovirus (CMV) Infection – This is a viral infection caused by the cytomegalovirus, which is a common virus that can infect people of all ages. In most healthy individuals, CMV infection is asymptomatic or may cause mild flu-like symptoms. However, when a person is infected for the first time, it is referred to as a primary infection. During pregnancy, primary CMV infection can be transmitted to the fetus, potentially leading to congenital CMV infection. The virus can remain dormant in the body and reactivate later, but primary infection is particularly concerning during pregnancy due to the risk of transmission to the unborn child.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2023-508643-46-00Protocol codePOL PRENATAL CMVEstimated enrolment200 patientsSponsorInstytut Matki I Dziecka

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