Objective To identify the presence of parvovirus B19 infection as a possible cause of fetal loss in the third trimester.
Design Prospective study of women experiencing third-trimester intrauterine fetal death (IUFD).
Setting All cases of IUFD at Danderyd Hospital from 1992 to 1998.
Population Ninety-three women with IUFD in 33,759 deliveries (0.3%).
Methods Detection of B19 DNA by polymerase chain reaction (PCR) in placental and fetal tissue. Placental pathology and B19-specific immunohistochemistry. Maternal serology in consecutive samples.
Results Among 93 cases of IUFD, seven (7.5%) had detectable B19 DNA in freshly-frozen placental tissue. The detection of B19 DNA in these tissues was confirmed by detection of B19 DNA in six separately stored paraffin-embedded placental tissues. No other explanations for the fetal deaths were found. None of the women had experienced any clinical signs of infection prior to fetal demise. None of the seven fetuses were hydropic. Histopathologic examination of the placentas revealed only minor abnormalities. Serology on maternal samples at birth revealed delayed or absent B19 IgG responses in five of seven cases. Two women were B19 IgG seropositive at the time of delivery but had unusual infection patterns; persistent viraemia for at least five months before birth in one case and likely persistence or re-infection by B19 in the other.
Conclusion In our study, 7.5% of IUFDs in the third trimester may have been caused by parvovirus B19 infection, without signs of fetal hydrops. This finding indicates that B19 PCR should be included in the routine investigation of IUFD.