Legionnaires’ disease in mothers: Can it have an effect on the fetus?

What happens if a pregnant woman contracts Legionnaires’ disease? What will happen to the fetus? I know she cannot be infected by other people, but could she contact the bacteria and contract the disease?


Legionnaires’ disease is a pneumonia that is often severe with a high mortality rate, if the pneumonia is not diagnosed early. The risk to the fetus can be high for 2 reasons:

1) The mother can be severely-ill with a life-threatening disease. This would in turn threaten the life of the fetus.

2) The Legionella bacterium could cross the placenta and infect the fetus. This would likely harm the fetus and may cause permanent damage. This scenario should be discussed with the obstetrician and we can email him/her information on outcome and therapy. Please show the doctor this email and ask the doctor to contact us.

If the mother was diagnosed early in the course of pneumonia, the antibiotics that are effective cross the placenta and would protect the fetus. These antibiotics are not harmful to the fetus with one exception: doxycycline may cause some problems. However, the more effective antibiotics (macrolides such as azithromycin, clarithromycin, erythromycin) are not harmful to the fetus. The quinolones  (levofloxacin, moxifloxacin, ciprofloxacin) are also highly effective and are not considered harmful to the fetus, but clinical experience is limited. Cartilage damage might occur in infants, but no such cases have been reported in fetuses.