This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Treponema pallidum crosses placenta 
Select and explain. 
A. After 36 weeks, B. After 28 weeks, C. After 2nd trimester, D. At any stage of pregnancy
D: At any stage of pregnancy
Answer: D: At any stage of pregnancy 
Explanation: Transmission of Treponema pallidum from an infected woman to her fetus across the placenta may occur at any stage of pregnancy, but the lesions of congenital syphilis usually develop after the 4th month of gestation, when "fetal immunologic" competence begins to develop. Ref : Ananthanarayana textbook of Microbiology 9th edition Pgno : 372