Pregnant woman standing and touching her stomach

CMV & Pregnancy

CMV & Pregnancy

CMV is a common virus that infects people of all ages, regardless of ethnicity or socio-economic class, and most people have been exposed to CMV at some point in their lifetime without their knowledge. In fact, it is estimated that 50-80% of adults in the United States have been infected with CMV by the time they reach 40 years old. Once CMV is in a person’s body, it stays there for life.

People with an active CMV diagnosis will sometimes shed the virus in body fluids, such as urine, saliva, blood, tears, semen, and breast milk. Shedding of the virus may take place intermittently, without any detectable signs, and without causing symptoms.

Did you know 1 per every 200 children is born with congenital CMV in the United States, making it the most common congenital viral infection affecting newborns? CMV can be easily transmitted to an unborn child by a pregnant mother experiencing a CMV infection, an often symptomless virus.

Know your risk!

Every woman of childbearing age can learn her CMV status. Before you plan to conceive, ask your doctor to have a blood sample drawn for a CMV IgG and IgM antibody tests. If your doctor refuses, ask them to document their refusal in your chart.  

CMV Screening Before and During Pregnancy

Women can be tested for CMV prior to pregnancy – ask your doctor to run CMV IgM and IgG antibody tests. If a woman has been exposed to a recent CMV infection, it is recommended that she wait until her CMV IgM antibody levels decline to an undetectable level, and her CMV IgG avidity index climbs to a highly favorable percentage, before trying to conceive. This can take anywhere from six to twelve months. It is important to wait until the CMV infection has resolved because it minimizes the risk of CMV transmission from the pregnant woman to her baby in utero.
If you are already pregnant, you can request that CMV IgM and IgG antibody lab tests be added to your routine labs. These tests are relatively inexpensive and are covered by most insurance plans.

Here is an explanation of IgG and IgM antibody test results and what they mean for your pregnancy:  

IgG negative
IgM negative
Not previously CMV infected
At risk for primary infection
IgG positive
IgM positive
Recent CMV infection
IgG positive
IgM negative
Past CMV infection that is not recent

No history of prior CMV infection – Be sure to practice the CMV prevention precautions to help minimize your risk of contracting CMV during pregnancy. You shouldn’t need any further CMV antibody testing unless you begin showing signs of a CMV infection, or if your baby shows signs of a possible CMV infection during a routine ultrasound. 
Recent CMV infection – If you are not already pregnant, ask your doctor how long you should wait before you try to conceive. And if your doctor doesn’t know or you aren’t sure, contact us to be connected with a CMV expert. If you are already pregnant, ask your doctor if you should receive extra ultrasounds to track your baby’s development in utero and to confirm that your baby does not show any prenatal signs of CMV infection. If your baby does show signs of CMV infection in ultrasound, an amniocentesis may be necessary to find out whether your baby has a CMV infection.
Past CMV infection that is not recent – It is recommended that you practice CMV prevention recommendations during pregnancy because it is still possible that a recurrent CMV infection or an infection with a different strain of CMV may cause mild harm to your baby. These infections are rare and generally result in less serious disability than primary infections.

CMV Screening During Pregnancy

Sometimes a pregnant woman will need to be tested for CMV when an ultrasound catches abnormalities that could be caused by CMV or another infectious disease.
If one or more of the following signs are identified during an ultrasound, an amniocentesis should be done to confirm a congenital CMV infection:

  • Placental thickening
  • Organomegaly - abnormal enlargement of organs
  • Hepatomegaly – abnormal enlargement of the liver
  • Splenomegaly – abnormal enlargement of the spleen
  • Pyelectasis - dilation of the renal pelvis, the funnel-like dilated proximal part of the ureter (muscular tubes that propel urine from the kidneys to the urinary bladder) in the kidney (also a marker for Down Syndrome)
  • Megaloureter – abnormal dilation of the ureter
  • Ascites - gastroenterological term for an accumulation of fluid in the peritoneal cavity (is a potential space between the parietal peritoneum and visceral peritoneum; that is, the two membranes that separate the organs in the abdominal cavity from the abdominal wall)
  • Fetal hydrops - accumulation of fluid in the fetal compartments
  • Abnormality of amniotic fluid
  • Microcephaly – small head circumference, more than two standard deviations smaller than average
  • Cerebral ventriculomegaly – dilation of the lateral ventricles of the brain
  • Intracranial calcifications - the build-up of calcium salts in the soft tissue of the brain
  • Hyperdense image in thalamic arteries
  • Periventricular echodensities
  • Hepatic echodensities
  • Intestinal echodensities
  • Cystic structures in the germinal zone

If a pregnant woman is diagnosed with CMV during her pregnancy, her doctor should perform an amniocentesis to determine whether congenital CMV has passed to her unborn baby.
Recent studies indicate that Cytomegalovirus Immune Globulin Intravenous (CMV-IGIV) treatment may reduce the risk of congenital infection and/or disease in an unborn baby when given to pregnant women experiencing a primary CMV infection. Learn more.

Pregnancy After a CMV Baby

​Having one child with congenital CMV does NOT make you more prone to having another. There is no increase in risk for having another child born with congenital CMV. However, rushing into another pregnancy before your primary CMV infection is resolved may increase the risk of CMV transmission to your next baby.

Women who have experienced a CMV diagnosis during pregnancy, a fetal loss due to CMV, or a newborn with congenital CMV should discuss these factors with their doctor, who may recommend drawing CMV IgM and IgG antibody labs. If you are experiencing an active CMV infection, most experts recommend that women wait six to twelve months before trying to conceive again. Be patient, your peace of mind is worth the extra time consideration so the infection may appropriately resolve, ultimately ensuring a healthier start to pregnancy for you and your new baby.

To find out months and years down the road that this virus is common but preventable makes me so angry sometimes, but so happy to know that the education I have received now, can prevent other families for enduring what we have.
— Erica, Mother