Hepatitis E virus (HEV) infection among pregnant women is severe, often leading to fulminant hepatic failure and death, with mortality rates up to 15-25%. Studies suggest that differences in genotypes/subgenotypes, hormonal and immunological changes during pregnancy may contribute to the severe consequences for pregnant women with HEV. Although the increased mortality among pregnant women predominantly is seen in developing countries where genotype 1 is endemic, there are also large differences in mortality among pregnant women within these countries. The reason for this is not clear.