Which of the following is a known risk factor for non-immune hydrops?

Non-immune hydrops, characterized by abnormal accumulation of fluid in fetal compartments, can arise from various underlying conditions, and infection or anemia serves as a well-recognized risk factor for its development. Infections such as parvovirus B19, syphilis, or cytomegalovirus can lead to placentomegaly and fetal anemia, which may trigger heart failure or cardiovascular compromise in the fetus. This fluid accumulation is indicative of non-immune hydrops.

Conversely, blood type incompatibility primarily leads to immune hydrops, as it results in hemolytic disease of the newborn. Conditions like advanced maternal age and high blood pressure are more associated with other obstetric complications but do not have a direct causal link to non-immune hydrops. Therefore, understanding the etiology of non-immune hydrops emphasizes the importance of infections and anemia as critical risk factors.