The frequency with which tubercle bacilli are carried in the umbilical blood stream from the placenta to the fetus is not well known. If one judges by the incidence of demonstrable tuberculous lesions in the fetus and in the new-born infant, the transmission of the bacilli by way of the umbilical vein is extremely rare. Cases of undoubted congenital tuberculosis in a stillborn infant1 and in several new-born infants dying soon after birth with generalized tuberculosis2 are cited in the literature. In these cases the lesions were usually most marked in the liver and its regional lymph nodes.
There is evidence, however, that the tubercle bacilli might be transmitted by way of the umbilical vein more frequently than is indicated by the finding of tuberculous lesions in the fetus and in the new-born infant. Cases have been reported in which tubercle bacilli were present in the fetus, although
SIEGEL M, SINGER B. OCCURRENCE OF TUBERCLE BACILLI IN THE BLOOD OF THE UMBILICAL CORD AND IN THE NEW-BORN INFANTS OF TUBERCULOUS MOTHERS. Am J Dis Child. 1935;50(3):636-641. doi:10.1001/archpedi.1935.01970090066006