This complication is rare, because the uterus in most cases, on account of the effects produced upon its circulation, nerve-supply, and mucous membrane especially, will not retain the ovum, and conception does not take place. The uterus being more vascular, and subject to congestions that affect the placental attachment injuriously, miscarriages are likely to occur. It is also morbidly sensitive to the pressure of the ovum, while the mucous membrane is rendered incapable of decidual changes. The retentive power of the uterus is further interfered with from the irregularity of its growth: the fibres where the tumor exists, being under a morbid influence, cannot partake of the regular hypertrophy necessary to normal gestation. There is something of uniformity in the circumstances under which the coexistence of pregnancy and fibrous tumor is observed. The nearer the tumor is situated to the mucous membrane, the less likelihood of pregnancy--the more remote, the greater the tolerance of pregnancy. Tumors that occupy the wall of the corporal portion {252} are conducive of sterility. Those in the cervical portion of the corporal and the cervical zone are more likely to be accompanied with pregnancy than those situated in other parts of the organ. While the reader will find these statements borne out by his experience as general facts, he will also discover that pregnancy is occasionally compatible with almost any form, variety, or position of tumor. When this complication occurs, it does not generally influence the process of gestation or the condition of the tumor. The main symptoms depending on it are those caused by pressure. When small this is not very considerable. Complication with labor generally gives rise to more apprehension than difficulty. Most of the cases of labor terminate spontaneously and happily, and the others are generally within reach of the less destructive modes of delivery. Labor more frequently decidedly affects the growth of the tumor, in the majority of cases causing its disappearance during the process of involution. The cervical polypi affect labor less, and are less affected by labor, than any other variety of the tumor. If small, they are sometimes merely pressed to one side or into the hollow of the sacrum, and the head passes by them; if a polypus is large, the head of the foetus carries it before it beyond the vulva, where it remains until the child is expelled, when it may recede into the vagina.