Advocating for cytomegalovirus maternal serologic screening in the first trimester of pregnancy: if you do not know where you are going, you will wind up somewhere else.

Congenital cytomegalovirus infection is an important health problem for the individual and the community. Although it could derive from both primary and nonprimary maternal infection, the prospective risk of congenital infection in seronegative pregnant women is 4 times than that of immune women. Maternal serology is the only reliable screening tool in pregnancy that would identify up to 50% of all congenital cytomegalovirus infections, by yielding positive immunoglobulin M and immunoglobulin G and low immunoglobulin G avidity in approximately 0.5% of the population at 11 to 14 weeks. The exceptionally high risk for young parous seronegative women planning a second pregnancy makes a compelling case for offering serologic screening as soon as pregnancy is planned or diagnosed and by the end of the first trimester. The 11- to 14-week consultation has become an unmissable one worldwide and would represent the most practical compromise if only 1 sample can be taken. Valaciclovir that can be safely used in the early fetal period decreases vertical transmission by 70% and should be implemented as early as possible after maternal infection. Facilities for diagnosis and treatment are available in high- and middle-income countries through laboratory and fetal medicine networks. Amniocentesis with amplification of the viral DNA by polymerase chain reaction in the amniotic fluid is a reliable diagnostic test but chorionic villi sampled by chorionic villus sampling could achieve the same performance 2 months earlier. Fetal imaging of a known infected fetus yields a negative predictive value on symptoms at birth and congenital handicap of between 95% and 99%, and prenatal treatment of infected fetuses decreases the occurrence of symptoms at birth and at 2 years of age.