Antibodies given to pregnant people to target cytomegalovirus appeared to have no benefits for their children by age two, suggests a follow-up study funded by the National Institutes of Health. The virus can cross the placenta and infect the fetus, potentially leading to hearing loss, vision loss, intellectual disability, seizures, loss of coordination or weakness, and/or death. Full effects of the infection during pregnancy may not become apparent until a child is two years old. Like the original study, which assessed infants born to individuals receiving the formulation in early pregnancy, the current study found no differences in health outcomes between pregnant individuals receiving the treatment and those given a placebo.
The study was conducted by Brenna L. Hughes, M.D., of Duke University and colleagues in the Maternal-Fetal Medicine Units Network funded by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development. It appeared as a letter in the New England Journal of Medicine.
Background
Cytomegalovirus is a common virus that can infect people of all ages. In healthy people with a functioning immune system, the virus often doesn’t cause symptoms. However, if a pregnant person is infected with cytomegalovirus, it may cross the placenta and cause serious problems for the developing fetus, particularly in early pregnancy. Infection in pregnancy is associated with stillbirth, newborn death, deafness, and cognitive and motor delays. Roughly 10% of infants who were exposed to the virus in the womb have symptoms at birth and approximately 25% will develop a disability by age two.
In a 2021 study, the authors gave cytomegalovirus antibodies to pregnant people diagnosed with the infection before the 24th week of pregnancy. The antibodies were collected from donors who previously had the infection. Roughly 400 participants received either a monthly infusion of antibodies or a placebo until they gave birth. There was no significant difference between the groups in newborn or fetal death or infant cytomegalovirus infection at three weeks old.
For the current study, researchers evaluated the children periodically until they were two years old.
Results
Death or cytomegalovirus infection with severe disability occurred in 13.4% of children who received the antibody formulation and in 10.1% of those in the placebo group, results that did not differ significantly between the groups.
Significance
The authors noted that the CMV antibodies given in pregnancy did not improve hearing or developmental outcomes at 2 years of age. They concluded that the study results, along with those of the previous study, do not support giving the antibody in early pregnancy to people with cytomegalovirus infection.
Reference
Hughes, BL, et al. Randomized trial of hyperimmune globulin for congenital CMV infection—2-year outcomes. The New England Journal of Medicine. 2023. 10.1056/NEJMc2308286 
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