Treponema pallidum crosses placenta:: (A) After 36 weeks, (B) After 28 weeks, (C) After 2nd trimester, (D) At any stage of pregnancy
Answer is D. 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.