Infants may acquire tuberculosis (TB) by the following means: Transplacental spread through the umbilical vein to the fetal liver Aspiration or ingestion of infected amniotic fluid Airborne inoculation from close contacts (family members or nursery personnel) About 50% of children born to mothers with active pulmonary tuberculosis develop the disease during the first year of life if chemoprophylaxis or bacille Calmette-Guérin (BCG) vaccine is not given.