If I have had tuberculosis but it is no longer active in my system, can it affect my chances of becoming pregnant? Also, is it dangerous to the fetus?

G.R.

When people talk about tuberculosis (TB), an infection caused by the bacterium Mycobacterium tuberculosis (MTB), they're usually referring to cases involving the pulmonary (lung) manifestations, which are those of a chronic pneumonia. The patient has cough, fever and weight loss. But tuberculosis also can invade the other organs of the body, most commonly the bone marrow, the liver and the lymph nodes. Most people infected with MTB have no symptoms other than a positive skin test. More than two billion people in the world are infected with the organism. The lifetime risk of active tuberculosis (symptomatic disease) is about 10 percent.

I would like to know whether you had active disease at some point. (It sounds like you did, because you state that the disease is no longer active at this time.) If your tuberculosis was not active, and you only had a positive skin test, then it should have no effect on your future ability to have a baby. Even if you had active pulmonary tuberculosis in the past, that by itself should not affect your fertility. If the infection spread outside of the lung and infected your uterus, then infertility could be a problem. Infection of the endometrium, the lining of the uterus, can be associated with future infertility, but it by no means guarantees that you will not be able to have children.

What if the tuberculosis becomes active during pregnancy? Well, if the tuberculosis is confined to the lungs, as is usually the case, there is little risk to the fetus. Most of the drugs used to treat TB are safe in pregnancy and should be given. If the infection involves organs other than the lymph nodes, however, there can be effects on the fetus. In a recent study published in the New England Journal of Medicine, researchers found that pregnant women with active TB outside of the lungs and lymph nodes were more likely to need prenatal hospitalization, and their babies were more likely to have problems after birth. But remember that the above study included only women with active disease outside of the lungs. If your infection is inactive, especially if it was confined to the lungs, you really should have nothing to worry about.