Adverse effects of maternal enterovirus infection on the fetus and placenta.

Gestational outcome in a murine model of congenital enterovirus infection was evaluated. Pregnant mice were inoculated intravenously with Theiler's murine encephalomyelitis virus (TMEV), a murine enterovirus, or with BHK 21 cell lysate (control) at 6-7 days of gestation (early) and sacrificed 6 or 12 days later, and their placentas and fetuses were studied. High rates of gross and histologic abnormalities (50%-87%) were seen in placentas and fetuses from dams infected with TMEV and sacrificed 6 days later. TMEV-infected dams sacrificed 12 days after inoculation had lower rates of placental-fetal abnormalities (25%-57%) but an additional 42% rate of complete pregnancy loss. Pregnancy loss (9%) and placental-fetal abnormalities (4%-7%) were uncommon in control animals. Rates of fetal abnormalities and placental infection in infected dams exceeded fetal viral infection, suggesting that TMEV infection adversely affects pregnancy either directly by fetal damage or indirectly by placental compromise.