We have now evaluated the prevalence of detectable parvovirus B19 DNA in placental tissue from normal births. A total of 53 unselected placental tissues were collected, stored and analysed in the same way as that described in our article. The samples were collected during May, which normally is the time of year when parvovirus B19 infections are common. All tissue samples were found B19 DNA negative by polymerase chain reaction. The presence of B19 DNA in placental tissues from our previously published cases of third-trimester intrauterine fetal deaths was thus significantly higher than in the present cases of normal births (P= 0.05).
We agree that fetal loss occurs only a small proportion of B19 infected mothers. However, our finding that 7.5% of third-trimester intrauterine fetal deaths were associated with parvovirus B19, makes this virus one of the most common infectious agents found in intrauterine fetal deaths. Since maternal B19-specific serology was not sufficient for diagnosis we therefore recommend routine investigation of B19 DNA in placental and fetal tissues, by polymerase chain reaction, in cases of third-trimester fetal deaths.