From the Guidelines
Cytomegalovirus (CMV) infection during pregnancy poses significant risks, with the chance of transmission to the fetus ranging from 30-40% for primary infection, as noted in the study by 1. The risk of transmission is highest for women who acquire primary CMV infection during pregnancy, with approximately 30-40% of these cases resulting in congenital infection, as reported in the study published in MMWR Recommendations and Reports 1. In comparison, the risk of congenital infection after recurrent CMV infection is significantly lower, ranging from 0.15% to 1.0%, as indicated in the same study 1. Key factors influencing the risk and severity of CMV infection in pregnancy include the timing of the infection, with first-trimester infections typically resulting in more severe fetal effects, and the woman's previous exposure to CMV, with primary infections posing a greater risk than recurrent infections. Pregnant women can reduce their risk of acquiring CMV infection by practicing good hygiene, including thorough handwashing after contact with children's bodily fluids, avoiding sharing food or utensils with young children, and cleaning toys or surfaces that may have been exposed to saliva or urine, as suggested by guidelines for preventing opportunistic infections 1. Currently, there is no approved vaccine for CMV, and antiviral treatments during pregnancy are generally only considered in specific cases under specialist guidance due to potential side effects, as noted in the guidelines for the prevention of opportunistic infections in persons infected with human immunodeficiency virus 1. Given the potential severity of congenital CMV disease, which can include hearing loss, vision impairment, developmental delays, and other neurological problems, it is crucial for pregnant women and their healthcare providers to be aware of the risks and take preventive measures to minimize exposure to CMV. The most recent and highest quality evidence, such as the study published in MMWR Recommendations and Reports 1, should guide clinical decision-making regarding CMV infection in pregnancy, prioritizing the health and well-being of both the mother and the fetus. In the absence of a vaccine, preventive measures and careful management of CMV infection during pregnancy are critical to reducing the risk of congenital infection and its associated morbidity and mortality. Therefore, pregnant women should be advised to practice good hygiene and avoid exposure to CMV, and healthcare providers should be vigilant in monitoring for signs of CMV infection and providing appropriate care and treatment as needed, based on the most recent and highest quality evidence available 1.
From the Research
Chances of CMV Infection Affecting Pregnancy
- The chances of CMV infection affecting pregnancy are significant, with congenital CMV infection occurring in approximately 1 in 150 live births in the United States, leading to permanent disabilities in approximately 1 in 750 live-born children 2.
- Primary CMV infection during pregnancy can lead to congenital CMV infection, with transmission rates as high as 50% in women who acquire primary CMV infection during pregnancy, and less than 2% in women with nonprimary infection 3.
- The risk of congenital CMV infection is higher when the infection occurs before 20 weeks of gestation, and severe fetal effects are more common during this period 4.
- CMV infection can cause a range of symptoms in newborns, including hearing loss, vision loss, and cognitive impairment, with approximately 1 in 10 infants who acquire CMV in utero showing clinical signs at birth, and an additional 10 to 15% developing late-onset sequelae 3.
Prevention and Treatment of CMV Infection
- Good hygiene practices, such as avoiding close contact with young children and practicing good hand hygiene, are currently the most effective strategy for preventing CMV infection during pregnancy 2, 4.
- Antiviral treatment, such as valaciclovir, has shown promise in reducing the rate of fetal CMV infection following early maternal primary infection, with a recent study finding that valaciclovir at a dose of 8g/day was effective in reducing the rate of fetal CMV infection 5.
- CMV hyperimmune globulin (HIG) has also been investigated as a potential treatment for preventing congenital CMV infection, with some studies suggesting that it may be effective in reducing the risk of congenital CMV infection, although the evidence is not yet conclusive 5, 6.
Diagnosis and Screening of CMV Infection
- Diagnosis of primary maternal CMV infection during pregnancy is typically based on seroconversion or detection of specific immunoglobulin M (IgM) and IgG antibodies in association with low IgG avidity 4.
- Prenatal diagnosis of fetal CMV infection is imperfect and typically involves amniocentesis performed at least 8 weeks after presumed maternal infection and after 17 weeks of gestation 4.
- Screening for CMV infection during pregnancy is not currently routine, although some studies suggest that it may be beneficial in identifying women at risk of congenital CMV infection and providing targeted prevention and treatment strategies 6.