PHENOMENA OF PREGNANCY.
The Pelvis.
The bony pelvis is unaltered; the articular portions only are those modified in pregnancy. And these chiefly occur in the symphysis pubis.
1st. Symphysis Pubis.—If we can not agree with Jacquomier and Mme. Boivin that the symphysis relaxes to the point of disjunction, we must admit that it becomes a lax joint during gestation, as Budin has proved. The two bones can become slightly displaced, which is appre ciated by the finger placed under the symphysis when the woman, stand ing, lifts now one leg, now the other. But these are always limited movements, and are not sufficient, as was formerly believed, to allow increase in the size of the pelvis. When the relaxation is greater, it is accompanied by other phenomena, and is then called relaxation of the symphysis. (See Diseases of Pregnancy.) There is only an increase in size of the interpubic cartilage from im bibition of a serous fluid, which relaxes the cartilage, and also renders it elastic, and causes it to resemble the intervertebral discs. Its fibres become red and long; it is a phenomena that is analogous to what occurs in certain animals, and which seems to be more marked in women the more children they have bad.
2d. Sacro-iliac Synehondrosis.—The intra-articular cartilages here undergo the same changes as in the symphysis pubis.
Zaglas and Duncan state that the sacrum revolves about a transverse axis passing through the second sacral vertebra; this thrusts the promon tory forward about .9 of an inch, and the coccyx backward. 19 of an inch, when the woman leans far forward. But when she sits or stands, the sacrum projects backward and the coccyx forward, with relaxation of the sacro-sciatic ligaments. After the fourth month Jacquemier has found this, and it increases with pregnancy.
3d. Sacro-coccygeal Articulation. —Always movable, this joint becomes more so as pregnancy goes on; at the close of gestation it is so great that, at delivery, the coccyx can move back .39 to 1 inches. This is always painful, and in some women agonizing.
Excepting this movement, and the truly useful increase in the coccy pubic diameter, it may be said that the changes in the pelvic articula tions are more harmful than useful, insufficient in an abnormal, and useless in a normal pelvis. These relaxations only serve to make the pregnant woman walk unsteadily; and (I'ajot) have a very doubtful value.
External Genitals.—The Vagina.
Only in advanced pregnancy (at the third or fourth month) do any appreciable changes occur in the external genitals.
I. Vulva.—This becomes moister, more lubricated, swells towards the end of pregnancy, and becomes the seat of more or less oedema, especially in the labia majors which may have varices in them, which are prolonged up to the vagina. The urinary meatus is red, prominent and more or less pigmented. The mucous membrane of the vulva becomes dark red.
IL Vagina.—The vagina is altered both anatomically and physiologi cally. Lengthening about the fourth month from the rising of the uterus, it, however, shortens later on from descent of the womb and engagement of the fcetus. The upper part widens. It becomes violet-red, the papilla] may be prominent, constituting (Devine) granular vaginitis.
The secretions greatly increase, so that erythema of the thighs, and erosion of the labia, with painful pruritus or more or less abundant leu corrhcea result therefrom.
The chief changes are those in its structure. Rouget has proved that the muscular tissue hypertrophies, and, instead of an irregular tissue, the fibres arrange themselves in planes. Thus we see bow the vagina gains contractility and extensibility, how it can dilate as the fcetus and its appendages pass through it, and how, later, it returns to the normal. It can also aid the uterus and abdominal muscles in the last efforts to expel the child.
The vascular system also developes, and not rarely we feel a beating artery at the fund us of the vagina, Osiander's vaginal pulse. We have once or twice felt this pulsation in the posterior lip of the os tine.