Screening and Treatment In Pregnancy

Guidelines for screening and treatment of CMV in pregnancy differ between Canada, Europe, Australia/New Zealand and Europe. Below we provide an overview of the guidelines from around the world and a synthesis of the most recent research. 

If you've been diagnosed with CMV during pregnancy, you're not alone—and there may be treatment options to help. In some cases, doctors may recommend antiviral medications, like valacyclovir, to lower the chance of passing the virus to your baby or to help reduce how seriously your baby might be affected. These treatments are still being studied, but early research is hopeful. Every pregnancy is different, so it’s important to talk with a doctor who specializes in high-risk pregnancies to see what’s best for you and your baby. The National CMV Foundation is here to support you and provide the latest information as research continues to grow.

1. American College of Obstetricians and Gynecologists – USA

• Screening: Routine screening of all pregnant women for CMV is not recommended. Instead, clinicians should counsel high-risk patients (e.g., those with young children or child-care work) on hygiene to reduce risk. AJOG

• Treatment: Antiviral therapy during pregnancy (e.g., valacyclovir) is not recommended outside of research settings. AJOG

• Practice Bulletin No. 151 also offers FAQs and counseling guidance. ACOG+1

2. Royal College of Obstetricians and Gynaecologists – UK

• Screening: Universal screening during pregnancy is not recommended; CMV testing is usually only done if a pregnant person shows symptoms or fetal ultrasound detects anomalies. RCOG+1

• Treatment: If primary CMV infection occurs in the first trimester, valacyclovir may reduce risk of transmission. Confirmed fetal infection warrants frequent ultrasounds (every 2‑3 weeks) and possibly MRI. Newborns born to infected mothers should be tested within 21 days. Symptomatic infants may benefit from antiviral treatment (valganciclovir or ganciclovir). RCOG+1

3. Society of Obstetricians and Gynaecologists of Canada 

• Screening: Routine screening for all pregnant women is not recommended. JOGC+1 High‑risk women (e.g., those with young children or who are childcare workers) may be offered first-trimester IgG and IgM testing followed by IgG avidity if IgM‑positive (where available). JOGC+1

• Treatment: If primary CMV infection is confirmed in the first trimester, valacyclovir may be considered. Amniocentesis to diagnose fetal infection should be offered at least 7–8 weeks after suspected maternal infection and after 21 weeks’ gestation. JOGC+1

• Other: Routine use of CMV hyperimmune globulin is not recommended to prevent congenital CMV. Education on hygiene should be provided to all, regardless of serostatus. JOGCPMC

4. Society for Maternal-Fetal Medicine – USA

• Screening: Universal screening is not recommended at this time. Obstetrics & Gynecology+1

• Treatment: Valacyclovir or hyperimmune globulin during pregnancy should only be used within research settings, not in routine practice. PMC+1

Link: SMFM Consult Series #39 (Diagnosis and Antenatal Management of Congenital CMV)

5. European Congenital Cytomegalovirus Initiative (ECCI) – European consensus

• Screening:

  • First-trimester CMV serology is recommended. Seronegative women should be retested every 4 weeks until 14–16 weeks.

  • Universal screening may be considered depending on local epidemiology. PMCThe Lancet

• Treatment:

  • In cases of maternal primary infection (periconception or first trimester), oral valacyclovir 8 g/day should be started as early as possible until amniocentesis. The Lancet

  • Hyperimmune globulin (100 IU/kg every 4 weeks) is not recommended; high-dose (200 IU/kg every 2 weeks) may be considered in very early infection. PMC

• Fetal diagnosis & follow-up:

  • Perform CMV PCR on amniotic fluid from ≥17 weeks and ≥8 weeks after infection.

  • Serial ultrasound & MRI in the third trimester to assess prognosis.

  • In confirmed fetal infection, valacyclovir treatment may be considered after expert consultation.

• Neonatal management:

  • Neonatal CMV testing via PCR in first 3 weeks; symptomatic infants (especially with CNS or hearing issues) should be treated with valganciclovir, ideally before 1 month of birth.

  • Follow-up for at least 6 years if infection occurred in the first trimester; shorter follow-up if infection occurred later. The Lancet

 

Key Takeaways for Parents and Providers

• Valacyclovir may reduce the risk of passing CMV to a fetus, especially if taken soon after infection.

• Most studies show few serious side effects, but always talk to your doctor about risks and benefits.

• Treatment is not yet officially approved for CMV in pregnancy in the US, so it's important to work with a specialist, like a maternal-fetal medicine doctor.

• Research is ongoing, but the results so far are hopeful for families facing a cCMV diagnosis during pregnancy.
   

  Study             What They Did                    What They Found                         What It Means for Parents Italian Study (2023)                        Followed 447 pregnant women with CMV. Some took valacyclovir, some didn’t. Women who took valacyclovir had lower chances of passing CMV to their babies. Fewer babies were sick at birth. This real-life study supports using valacyclovir to reduce the risk of CMV affecting the baby. Randomized Trial (2020) A carefully controlled study gave some pregnant women valacyclovir and others a placebo (no medicine). Valacyclovir cut the risk of passing CMV to the baby by about 70%.                     This is strong evidence that valacyclovir works—especially when started early in pregnancy. Small Study on Sick Fetuses Gave valacyclovir to pregnant women whose babies already showed signs of CMV. More than 80% of babies were born without symptoms—better than in past cases with no treatment. Valacyclovir may help even if signs of CMV are already showing in the baby. Older Case  Series                    Gave valacyclovir to women and tracked results.                          Virus levels dropped and many babies developed normally, though some had hearing issues. Shows that the medicine can work, but long-term outcomes can vary. Combined Study (2023) Looked at results from multiple studies involving over 500 women. Valacyclovir reduced transmission and made it less likely babies would be sick at birth. The more data we collect, the more promising  valacyclovir looks— especially if started early. Review of 8 Studies (2022)        Reviewed studies of 620 women who were or weren’t treated with antivirals. Fewer babies got CMV when moms were treated. Most side effects were mild and reversible. Antiviral treatment appears helpful and safe, though more research is needed. Combo Treatment Study Tried valacyclovir with another treatment (immune globulin). Most babies were healthy; very few had hearing issues. No serious side effects. This combo could help when babies already show signs of CMV, but it’s still early research. European Guide- lines Support                   Experts reviewed the best available evidence.         Valacyclovir shown to help when started early in pregnancy. Doctors in Europe now recommend this treatment in certain situations.