Parvovirus B19 in Pregnancy: A Case Review

Parvovirus B19 has been identified as the cause of erythema infectiosum, a common childhood illness. Also known as fifth disease, this virus is highly contagious among school-age children, especially during the winter months when outbreaks within classrooms are widespread. The majority of adults have had the infection in childhood and are immune to recurrence. Approximately 40% of childbearing-age individuals, however, remain nonimmune and susceptible to infection. If acquired during pregnancy, parvovirus B19 infection can have devastating fetal consequences, especially if contracted in the second trimester. Vertical transmission of parvovirus B19 occurs more readily during this gestational period, and fetal loss rates of 8% to 17% have been reported as a result of severe fetal anemia and hydrops fetalis. Unfortunately, adults with parvovirus B19 infection are often asymptomatic and do not exhibit the classic slapped-cheek rash seen in childhood. More commonly, adults will exhibit atypical symptoms such as joint arthralgias. Maternal history of direct exposure to a confirmed case within the family or the presence of atypical symptoms warrants serum antibody screening. Although the presence of immunoglobulin G confirms immunity, any immunoglobulin M positivity will require ongoing fetal surveillance for evidence of fetal anemia and hydrops fetalis. Serial ultrasound imaging for 8 to 12 weeks with Doppler measurements of the peak systolic velocity in the middle cerebral artery are the mainstays of fetal monitoring. Referral to a maternal-fetal medicine specialist with experience in fetal blood sampling and intrauterine transfusion is recommended for any cases of hydrops fetalis or if a concern for severe fetal anemia exists.