Some tubercular women during pregnancy give no clinical evidence of an aggravation of the pulmonary disease, but these cases are exceptional. Tubercular women who apparently improve during pregnancy are likely to have a subsequent detrimental reaction. As tubercular cases, however, are prone to show exacerbations even if not pregnant, it is not possible to say that pregnancy is the sole cause of the progressive lesions in particular instances. Where there are no wide or deep areas of infection, there may be no recognizable damage from pregnancy, but advanced and active tuberculosis, with fever or cavity formation, does badly, especially if the throat is involved. The pressure of the enlarged uterus causes dyspnoea; the cough and fever may bring on miscarriage. Miscarriage, however, is rare in tuberculosis; it is more common in cardiac and renal diseases. Bernheim, in a series of 315 tubercular pregnancies, found that abortion occurred in 23 per cent. The later in gestation the tuberculosis becomes florid, the more likely it is that abortion will happen. Conception may take place at any stage of the tuberculosis, although women in the final stage are commonly sterile. Sometimes a woman will give birth to a sound child and die herself of tuberculosis a few days after the parturition. Pregnancy in consumptive women is not necessarily detrimental to each particular patient, nor is it, as a rule, a justification for emptying the uterus of even the viable fetus. Even when the tubercular condition grows worse during pregnancy it is not always possible to prove that the pregnancy itself is the cause of the deterioration. If the woman conceives in the final stage of pulmonary tuberculosis she will die, whether she goes on to term or not. Bonney[148] describes three cases of advanced pulmonary tuberculosis which were cured during pregnancy, by the bodily changes peculiar to that condition, but such results are altogether exceptional. [148] _Pulmonary Tuberculosis_, p. 550. Philadelphia, 1908.