THE INCIDENCE OF, AND FACTORS LEADING TO, PARVOVIRUS B19-RELATED HYDROPS-FETALIS FOLLOWING MATERNAL INFECTION - REPORT OF 10 CASES AND METAANALYSIS

Objectives: to clarify the approximation of the frequency of B19-relat ed nonimmune hydrops fetalis (NIHF), and to know the critical period d uring which maternal infection led to NIHF. Methods: we investigated t he characteristics of 10 cases of antenatal B19 infection diagnosed ov er the past 10 years in Miyagi prefecture, Japan, and performed a meta -analysis of these cases and those previously reported in the literatu re. Results: NIHF caused by intrauterine B19 infection was diagnosed b etween 11 and 23 weeks of gestation in 10 women over the past 10 years in Miyagi prefecture, Japan. The source of infection was the mother's older child in sir; out of 10 cases, and children at a kindergarten w here the mothers worked in two cases. The interval between the onset o f infection and the diagnosis of NIHF ranged from 2 to 6 weeks. B19 in fection was responsible for 10 (15.2%) in 66 cases of aetiology unknow n NIHF in this study, and for 57 (19.1%) of 299 cases of non-malformed or aetiology-unknown NIHF by meta-analysis of the literature. Meta-an alysis of the 165 reported cases of antenatal B19 infection, including the 10 cases described above, showed that there was a 10.2% excess ri sk of fetal death in women infected with B19 during pregnancy and a 12 .4% excess risk in women infected during the first 20 weeks of pregnan cy. Transplacental transmission was confirmed in 69 (24.1%) of 286 cas es. The mean gestational age at diagnosis of NIHF was 22.8 +/- 5.1 wee ks. The mean interval between the onset of maternal infection and diag nosis of NIHF was 6.2 +/- 3.7 weeks. Conclusions: these approximations will be useful for counselling and management for pregnant women, The critical period during which maternal infection led to NIHF correlate d with the hepatic period of hematopoietic activity. These findings su ggest that parvovirus B19 may have an affinity for erythroid lineage c ells at the hepatic stage of hematopoiesis, which may strongly influen ce the clinical features of fete-maternal B19 infection.