Pneumonia in pregnancy is a rare but very dangerous disease. In one series of 13,611 pregnancies there were 120 cases of pneumonia--eight-tenths of one per cent.; in another series of 1842 pregnancies two and three-tenths had pneumonia. Wallich,[143] in a study of the mortality of this condition, found that pneumonia causes abortion in one-third of the cases that occur during the first six months of gestation, and in two-thirds of the cases that happen between the sixth month and term. On the third day of the pneumonia the abortions are most likely to occur. The maternal mortality varies between 50 and 100 per cent. in the groups studied, and the fetal mortality is 80 per cent. in general, but about 40 per cent. for viable fetuses. The large size of the uterus in the last months of pregnancy interferes with the descent of the diaphragm in respiration, and the heart is likely to fail. The more advanced the pregnancy, the greater the danger to both mother and child from pneumonia. Among the dangers to the child is the imperfect oxygenation of its blood, and in a few cases the pneumococci reach the fetus. [143] _Annales de Gynécologie._ June, 1889 Randall, in a study of 190 pregnant women who had pneumonia, found a somewhat lower mortality than that observed by Wallich. In Randall's series 70 died (36.7 per cent.); of 118 who did not abort, only 12 died (10.7 per cent.). In a second group of 352 cases abortion happened in 58.8 per cent. Of 144 patients in the first six months of gestation, 22.08 per cent. died, but of those that aborted 52.08 per cent. died. Again, of 164 cases in the last three months, 30.49 per cent. died, but 70.12 per cent. died of those that aborted during these three months. Of 82 that aborted, 87.8 per cent. died. The mortality in women under 25 years of age was 13.33 per cent.; in women from 25 to 35 years, 23.2 per cent.; over 35, 22 per cent.