Why is rubella during the first three months of pregnancy associated with congenital heart disease?

When a woman is infected with the rubella virus during the first three months of pregnancy, the virus can cross the placenta and infect the developing fetus. This infection interferes with the complex embryological development of the heart, leading to congenital heart disease.1234

A specific and common association with prenatal rubella infection is patent ductus arteriosus, a condition where the vessel connecting the aorta and the pulmonary artery fails to close after birth. Because these structural lesions arise early in fetal development, the risk of malformation is highest during the first eight weeks of pregnancy, though it remains a significant concern throughout the first trimester. These defects are part of a group of conditions known as congenital rubella syndrome, which may also affect the eyes, brain, and large arteries.3421

It is important to note that these serious health outcomes underscore the ethical necessity of preventative healthcare, such as immunization, to protect both maternal and fetal well-being.1