**Core Concept**
Rubella infection in pregnancy poses a significant risk to the fetus, leading to congenital rubella syndrome (CRS). CRS is a condition characterized by the transmission of the rubella virus from the mother to the fetus during pregnancy, resulting in various congenital anomalies and fetal complications.

**Why the Correct Answer is Right**
The risk of CRS is highest when the rubella infection occurs during the first trimester of pregnancy, particularly between weeks 8 and 12. This is because the virus can cause damage to the developing fetus, leading to birth defects such as heart defects, hearing loss, vision impairment, and intellectual disability. The rubella virus infects the placenta and the fetal tissues, causing an immune response that results in the production of antibodies, which can lead to various complications.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the risk of CRS is highest in the first trimester, not in the second or third trimester.
**Option B:** This option is incorrect because while rubella infection in pregnancy can cause various complications, it is not a common cause of stillbirth.
**Option C:** This option is incorrect because while rubella infection in pregnancy can cause congenital anomalies, it is not a common cause of fetal growth restriction.

**Clinical Pearl / High-Yield Fact**
Rubella infection in pregnancy is a preventable cause of congenital anomalies, and vaccination against rubella is a crucial measure to prevent CRS. The rubella vaccine is usually administered to children in the first year of life, and it provides long-term immunity against the virus.

**Correct Answer:** A. The risk of CRS is highest when the rubella infection occurs during the first trimester of pregnancy.