The entire body participates in the changes brought about by pregnancy. The hips and breasts become fuller, the back broadens, and the woman puts on fat. She becomes mature in appearance, but, of course, the phenomena connected with alterations in the breasts and genitals are most important, and late in pregnancy, most conspicuous. The uterus exhibits the most marked alteration. From an organ that weighs two ounces, it becomes the largest in the body, and increases in size from two and one-half or three inches to fifteen inches. The typical pear-shape becomes spheroidal near the end of the third month, becomes pyriform again at the fifth month, and continues thus until term. Up to the fourth month the walls become thicker, heavier and more muscular, but as pregnancy advances, more and more tissue is demanded, until at the end, a muscle wall of only moderate thickness protects the ovum. Meanwhile the muscular functions of contractibility and irritability are greatly increased. At the fourth month the womb, which has occupied a position of anteversion against the bladder, rises out of the pelvis. It is now an abdominal organ and as it gets heavier and heavier, it rests a certain amount of its bulk on the brim of the pelvis. About the sixth month, the uppermost part of the uterus (fundus) is at the level of the umbilicus. At the eighth month, the fundus is found a little more than midway between the umbilicus and the ensiform cartilage. About two weeks before term, it reaches its highest point, the ensiform cartilage, and then sometimes sinks a little lower in the abdomen. The ovum, or egg, does not completely fill the uterine cavity at first, but grows from its side like a fungus until the third month. Then the uterine cavity is entirely occupied and thereafter the egg and the uterus develop at an equal rate. As the uterus rises in the abdomen, it rotates to one side, usually the right, forward on its vertical axis. [Illustration: Fig. 24.—Gravid uterus at the end of the eighth week. (Braune.)] The blood vessels and lymphatics also increase in size, number, and tortuosity. Many of the veins become sinuses as large as the little finger. This increased amount of fluid both within and without the uterus has a marked effect upon its consistency. The walls of the uterus, vagina, and cervix become softened, infiltrated and more distensible. There is also an increase in size and in number of the muscle cells. During pregnancy the uterine muscle exhibits a definite functional activity. Intermittent contractions occur, feeble at first, but growing markedly stronger as pregnancy advances. These are the contractions of Braxton Hicks. They are irregular and painless, but can be felt by the examining hand. At term they merge into, and are lost in, the regular, painful contractions of labor.