Placental transmission of novel pandemic influenza a virus.

The effects of maternal influenza on the fetus are not well understood. Viremia is believed to occur infrequently and thus vertical transmission appears to be rare. Highly pathogenic strains of influenza virus, such as avian influenza A (H5N1), are more likely to be transmitted across the placenta. Placental tissues of seven women with confirmed H1N1 infection were examined molecularly with RT-PCR and microscopically to investigate whether H1N1 virus vertically transmitted. We found no evidence for placental transmission of H1N1 virus in this study. In the absence of vertical transmission, adverse effects like neonatal seizures, encephalopathy, cerebral palsy, and even neonatal death can still occur. Since a significant knowledge gap exists for the effects of this novel virus on the fetus, further studies will be beneficial.