This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Physiology & Histology, Subject name: Gynaecology & Obstetrics
Which of the following agent's infection causes heavy placenta? 
Select and explain. 
A. HSV, B. CMV, C. Syphilis, D. HIV
B: CMV
Answer: B: CMV 
Explanation: Ans. b. CMVSerological testing for primary maternal cytomegalovirus (CMV) infection during pregnancy is not routine, but ultrasound studies are routine. Therefore, we evaluate placental thickening in women with primary CMV infection during pregnancy.Most are asymptomatic; however, some women have mononucleosis like syndrome.