What risk does a fetus face when the mother has been exposed to Parvovirus B19 during pregnancy?

When a mother is exposed to Parvovirus B19 during pregnancy, the primary risk faced by the fetus is fetal death and birth defects. Parvovirus B19 can lead to a condition known as fetal hydrops, which is an accumulation of fluid in the fetal compartments. This condition can be severe and can result in fetal demise if not managed appropriately.

Moreover, the virus can affect fetal erythropoiesis, leading to anemia, which can cause decreased oxygenation and potential developmental issues, contributing to the risk of various birth defects. The implications of Parvovirus B19 infection are particularly critical during the second trimester when the fetus is developing and the virus can disrupt normal growth patterns and organ development.

While other options may present potential risks under different circumstances, the most significant and direct impact of Parvovirus B19 in pregnancy is the risk of fetal death and the development of birth defects, making this the correct choice in this context.