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How can rubella infection during pregnancy cause congenital malformations?

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BRCA2 tumor suppressor gene on chromosome 13 — human genetic disease Photomicrograph of the *BRCA2* tumor suppressor gene on chromosome 13 of the human genome. Inactivation of this growth-regulating gene is associated with a higher risk of developing breast cancer.

Rubella infection during pregnancy causes congenital malformations when the virus crosses the placenta from the maternal bloodstream into the fetal circulation. This transmission can lead to congenital rubella syndrome, a condition characterized by defects of the eye, heart, brain, and large arteries.12

The risk of these malformations is highest when maternal infection occurs during the first trimester of pregnancy. Specifically, infection within the first eight weeks is associated with fetal malformation in more than 50 percent of cases, a rate that decreases to approximately 20 percent by the 16th week and drops sharply thereafter. Because of these severe developmental risks, it is essential for women of childbearing age who have not had a natural infection to be immunized prior to becoming pregnant.21