Congenital cytomegalovirus (CMV) infection is the most common congenital infection with a birth prevalence of 0.4% in Europe. It is the leading non-genetic cause of sensorineural hearing loss and a major cause of neurodevelopmental disabilities. The risk of intrauterine transmission is highest when primary infection occurs during pregnancy. Primary CMV infection is asymptomatic or causes non-specific symptoms and only serology can diagnose it with certainty.

The diagnosis of CMV infection is based on the combination of 2 or 3 serological markers and the interpretation of the results is more complex than for other infections and may require additional analyses and sometimes delay the diagnosis and the implementation of secondary prevention of CMV transmission to the fetus by the administration of valaciclovir. Indeed, the effectiveness of secondary prevention is conditioned by the early administration of treatment after the maternal primary infection.

The National Reference Center for Congenital CMV Infections at Necker Hospital, in collaboration with the virology laboratory at Paul Brousse Hospital, has developed the MyCMV "expert" tool, which is a decision-making algorithm that allows the interpretation of CMV serology and CMV PCR results.

The hypothesis of the study is that the use and provision of this MyCMV "expert" tool to health professionals (biologists, midwives and obstetricians) for the interpretation of virological results could avoid a delay in diagnosis and would allow patients to be referred more quickly to a prenatal diagnosis center for appropriate management of CMV infection.

The aim of the study is to evaluate the rate of detection of primary CMV infection in the first trimester of pregnancy using the MyCMV tool compared with the reference method (results interpreted by the centre's expert investigator).

Congenital cytomegalovirus (CMV) infection is the most common congenital infection with a birth prevalence of 0.4% in Europe. It is the leading non-genetic cause of sensorineural hearing loss and a major cause of neurodevelopmental disabilities. The risk of intrauterine transmission is highest when primary infection occurs during pregnancy. Primary CMV infection is asymptomatic or causes non-specific symptoms and only serology can diagnose it with certainty.

The diagnosis of CMV infection is based on the combination of 2 or 3 serological markers and the interpretation of the results is more complex than for other infections and may require additional analyses and sometimes delay the diagnosis and the implementation of secondary prevention of CMV transmission to the fetus by the administration of valaciclovir. Indeed, the effectiveness of secondary prevention is conditioned by the early administration of treatment after the maternal primary infection.

The National Reference Center for Congenital CMV Infections at Necker Hospital, in collaboration with the virology laboratory at Paul Brousse Hospital, has developed the MyCMV "expert" tool, which is a decision-making algorithm that allows the interpretation of CMV serology and CMV PCR results.

The hypothesis of the study is that the use and provision of this MyCMV "expert" tool to health professionals (biologists, midwives and obstetricians) for the interpretation of virological results could avoid a delay in diagnosis and would allow patients to be referred more quickly to a prenatal diagnosis center for appropriate management of CMV infection.

The aim of the study is to evaluate the rate of detection of primary CMV infection in the first trimester of pregnancy using the MyCMV tool compared with the reference method (results interpreted by the centre's expert investigator). We also aim to evaluate the dating of the maternal primary infection in weeks of amenorrhoea and additional tests given by the MyCMV tool compared with the reference method.

For the study, the medical information of patients for whom CMV serology including the search for CMV IgG and IgM antibodies is prescribed in the Necker-Enfants Malades or Paul Brousse hospitals, with positive CMV IgM antibodies or in the grey zone of the technique and for whom the date of start of pregnancy is known, will be reinterpreted with the MyCMV tool without consequences on the care of the patients.

Inclusion Criteria:

• Pregnant woman
• And for whom a CMV serology including the search for CMV IgG and IgM antibodies is prescribed at the Necker-Enfants Malades or Paul Brousse hospital or CHU Limoges
• And with positive anti-CMV IgM or in the grey zone of the technique
• And for whom the date of start of pregnancy is known
• And who does not object to the use of their data in the context of this research

Exclusion Criteria: NA

Pregnant women.

Pregnant women with prescription of a CMV serology including the search for CMV IgG and IgM antibodies, care at the Necker-Enfants Malades or Paul Brousse hospitals or CHU Limoges, with positive CMV IgM antibodies or in the grey zone of the technique and for whom the date of start of pregnancy is known.