[Illustration: Fig. 37.—The effect of the pains. The cervix begins to be “effaced.” (Bumm.)] [Illustration: Fig. 38.—The effect of the pains. The cervix is effaced, and the dilatation of the os begins. (Bumm.)] [Illustration: Fig. 39.—The effect of the pains. The cervix is effaced, and the os continues to dilate. (Bumm.)] Sometimes the labor may be preceded by some hours (two or three), or days (two or three), even weeks (two or three), by the rupture of the membrane, and sometimes when the structure is thick and tough, the rupture may be delayed until well into the second stage, or even until the child is born. In the latter case, the head comes out, covered with membrane. In the old days, this was called being “born with a caul.” It was supposed to be a lucky omen, but it was lucky only that the babe escaped suffocation. The membrane should be torn open quickly. The duration of this stage is variable. It is much longer in primiparas than multiparas. It averages sixteen hours in the former, and eight hours in the latter. Vomiting during this stage is quite common, but the pulse and temperature remain normal. The first stage of labor is usually under the entire control of the nurse. It is her responsibility. With complete dilatation of the os, the _second stage_, or stage of expulsion, begins, whether the membranes rupture or not. The presenting part, usually the head, passes from the cervix into the vagina. The vagina in turn gradually dilates from above downward until uterus, cervix and vagina form a single, wide channel of the same diameter. The child is driven forward by the uterine contractions, strongly reinforced by the abdominal muscles, which the patient uses vigorously. The onset of each pain is accompanied by a deep inspiration, followed by straining or bearing down with the abdominal muscles as in a highly exaggerated bowel movement. The patient holds her breath, braces her feet, fastens her hands on bed or attendant, and uses all the trunk muscles in the effort. The face becomes congested, the pulse quickened, she perspires some, and groans deeply during the contraction. The pain is extreme and is due partly to the stretching of the vagina and vulva and partly to the distention of deeper sensitive structures. When the head reaches the pelvic floor, the first change observed in the external genitals is the stretching (bulging) of the perineal body. Next, the anus becomes turgid, dilates slightly, the anterior wall becomes visible, and the hairy scalp of the child appears at the vulva. The actual expulsion of the head in a primipara is accomplished by a series of prolonged and severe contractions, accompanied by violent straining. [Illustration: Fig. 40.—The cervix is effaced, and the os dilated. The second stage begins. (Eden.)] [Illustration: Fig. 41.—Child in second stage of labor with bag of waters unruptured and presenting at the vulva. (Braune, from Barbour.)]