Fig. 2

Flowchart of the evaluation process to distinguish between primary infection and borderline serological results in the study population following a step-by-step diagnostic assessment. (According to current German Diagnostic Guidelines [43] cases with CMV IgG or IgM seroconversion and the results with positive or borderline CMV IgM were evaluated manually. The following parameters were obtained: gestational age at the time of the serological testing, serological control tests, and IgG avidity test. Confirmed cases: Detection of CMV IgG seroconversion. CMV IgG seroconversion proves primary infection. Detection of low CMV IgG, low-avidity CMV IgG in combination with positive CMV IgM levels. Low CMV IgG avidity and positive IgM detection indicate a primary infection during the last three to four months.)