Most cases of rubella have no complications. In adult women with rubella, arthritis is a common complication but it clears up after the infection. In rare cases, rubella infection can be serious, causing brain infection or abnormal bleeding. The most serious complication of rubella infection is the potential harm to a pregnant woman's developing baby. Outcomes of rubella infection in pregnancy may include miscarriage, abnormal fetal growth and birth defects that are known as congenital rubella syndrome (CRS). Birth defects may include heart conditions, hearing problems and developmental delay. Congenital rubella syndrome is more common if a woman catches rubella in the first trimester (approximately 14 weeks) of pregnancy.