Although cytomegalovirus (CMV) is highly transmissible during the primary maternal infection in the third trimester, there appear to be no serious consequences for the newborn, Israeli researchers report in the medical journal BJOG International.
Lead investigator Dr. Liat Gindes, of Chaim Sheba Medical Centre in Tel Hashomer, told Reuters Health that when infections occur in the third trimester of pregnancy, amniocentesis is probably not necessary and "the prognosis is usually good."
Gindes and colleagues note that although newborns born with CMV infection can developing hearing loss and neurodevelopmental disorders, it is not known if foetuses infected at a later stage of pregnancy have fewer effects.
To investigate, the researchers studied 28 women who developed CMV infection after 25 weeks of pregnancy. Maternal-foetal or -infant transmission was documented in 21 of the pregnancies. One woman terminated her pregnancy at 34 weeks following detection of CMV DNA in the amniotic fluid.
None of the 20 live newborns had symptoms of infection and no adverse effects were documented.
"Although third trimester CMV infection carries a high transmission rate," the researchers conclude, "it has no deleterious effect on the foetal outcome."
They add that this study was small and observational design only, performing amniocentesis to diagnosis third trimester intrauterine CMV infection appears to be an unnecessary invasive procedure.