<prompt> Causes of Hydrops fetalis:ParvovirusHerpesCMVHIV  <response>: Ans. A ParvovirusRef: Williams Obstetrics 25th Ed; Page No 309Parvovirus B19 is the most common infectious cause of hydrops fetalis.Parvovirus B19 infects fetal erythroid progenitor cells and cause anemia.Severe anemia leads to high-output cardiac failure and hydrops fetalis. 