A positive IgM for cytomegalovirus means that the infection is cytomegalovirus and is still a recent infection, now in the acute phase of the infection, and is clearly contagious. Because IgM is relative to IgG, if it is IgG positive, it means a previous infection that may not be significantly contagious now. Cytomegalovirus is a herpes virus that has some degree of impact on health. In adults, however, the effects are relatively minor and do not cause significant illness. Women who are pregnant and have cytomegalovirus infection, especially during the acute phase of the infection, need to have the pregnancy surgically terminated when it is detected. This is because cytomegalovirus has a significant impact on fetal development, mainly on hearing development and the central nervous system. The infection is not necessarily contagious and affects the fetus, but termination of pregnancy is usually recommended to avoid risks. If the pregnancy is to be continued, an amniocentesis is performed at 20 weeks of pregnancy to evaluate the effects on the fetus and to decide whether to continue the pregnancy.