We very soon recognized in consultation with the obstetricians that the pregnant woman was in a really dangerous condition if she contracted influenza. She was likely to have a termination of her pregnancy in the height of the infection, no matter how recent or how remote pregnancy had taken place. If pregnancy did not terminate, the chances of recovery were less than those of the non-pregnant woman; if it did terminate, the chances for recovery were still less. To the pregnant woman with pneumonia very little hope of recovery could be offered. I am indebted to Dr. Paul Titus, of the Obstetrical Department of the School of Medicine, University of Pittsburgh, for a report which includes the cases seen by himself and his assistant, Dr. J. M. Jamison, during this epidemic. Dr. Titus was kind enough to include in his report certain conclusions which merit consideration. The report is as follows: “A series of 50 cases, at all stages of gestation. Interruption of pregnancy occurred in 21, or 42 per cent., of the cases; 29, or 58 per cent., in which pregnancy was uninterrupted. Mortality of pregnant women developing epidemic influenza is higher than that of ordinary individuals, even though their pregnancy is undisturbed, since 14 of the 29 in whom pregnancy was not interrupted died, an incidence of 48–2/10 per cent. If a pregnant woman miscarries or falls into labor, the mortality increases to 80–9/10 per cent. (17 of the 21 in whom pregnancy was interrupted died). The period of gestation has less influence on the outcome than the interruption itself. Of 10 at term, 3 lived and 7 died after delivery. “Two main features of this condition as a complication of pregnancy are: First, pregnant women developing epidemic influenza are liable to an interruption of their pregnancy (42 per cent. aborted, miscarried or fell into labor); second, the prognosis, which is already grave on account of the existence of pregnancy, becomes more grave if interruption of pregnancy occurs. “The cause of the frequency of interruption of pregnancy is probably a combination of factors: (1) The theory of Brown-Sequard that a lowering of the carbon-dioxid content of the blood causes strong uterine contractions sufficient to induce labor. (2) The toxæmia causes the death of the fœtus, particularly if not mature, when it acts as a foreign body and is extruded (10 premature fœtuses were born dead, while 1 was born alive, although 9 out of 10 at full term were born alive and survived). “The cause of the frequency of death following interruption of pregnancy is also due in all probability to a combination of factors: (1) Shock incident to labor. (2) Increase from muscular labor of carbon-dioxid in blood already overloaded by the deficiency of the diseased respiratory organs. (3) Sudden lowering of intra-abdominal pressure by the delivery. (4) Lowering of blood pressure by the hemorrhage of the delivery. (5) Strain of labor on an already impaired myocardium.”