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10/1/2008 - Michael L. Socol, MD

Editor: Pamela D. Berens, MD


Parvovirus B19 is a single stranded DNA virus which causes erythema infectiosum, also known as fifth disease. Clinical manifestations include flu-like signs and symptoms, low-grade fever, malaise, arthralgia, and a classic “slapped cheek” rash. Maternal infection is most often contracted from an affected child. The secondary infection rate may be up to 50% in susceptible household contacts, although many pregnant women have pre-existing immunity. Maternal infection is typically mild or asymptomatic. Pregnant women with suspected exposure should have testing done to evaluate the need for monitoring for seroconversion. Infection is confirmed with acute and convalescent maternal serology documenting the presence of IgM antibody or a four-fold rise in IgG antibody. PCR analysis of amniotic fluid can be performed for diagnosis of fetal infection.

Maternal to fetal transmission is estimated to occur in 17 to 33% of maternal infections in pregnancy. Fetal infection may resolve without sequela but adverse outcomes are possible. Fetal infection can result in profound anemia and fetal hydrops, presumably secondary to aplastic crisis, but other etiologies have been proposed. Acute infection during pregnancy is associated with an increased risk of fetal death during early pregnancy (8-17% when diagnosed from 9-20 weeks), although infection diagnosed later in pregnancy appears less problematic. Parvovirus is a potential cause of non-immunologic hydrops. Hydrops most commonly occurs within eight weeks after the primary infection, with the median occurrence at 3 weeks. Fetal surveillance with weekly ultrasound examinations to evaluate for signs of hydrops during this time is reasonable. Middle cerebral artery peak systolic velocity waveform measurements can be used to determine fetal anemia. Spontaneous resolution of the associated hydrops has been reported in some cases, although this appears unlikely when hydrops is severe. If fetal hydrops develops, fetal intravascular intrauterine transfusion is recommended and is most often curative. Long-term sequelae are unusual in the absence of fetal hydrops.

Further Reading:

Duff P. Maternal and fetal infections. In: Maternal-Fetal Medicine: Principles and Practice. Editors: Creasy RK, Resnik R, Iams JD et al. 7th Edition, Saunders, 2013.

Enders M, Weidner A, Zoellner I et al. Fetal Morbidity and mortality after acute human parvovirus B19 infection in pregnancy: prospective evaluation of 1018 cases. Prenat Diagn. 2004;24:513.

Cytomegalovirus, Parvovirus B19, Varicella zoster and Toxoplasmosis in Pregnancy. ACOG Practice bulletin # 151, June 2015

Initial approval 10/2008; Major revision 1/2015; Revised 7/2016.


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