A short pause ensues, followed in two or three minutes by a return of the pains, which expel first the shoulders and then the trunk. As the body escapes it is followed by a rush of blood-stained liquor amnii. This is the fluid that has been pent up in the uterus by the obstructing body of the child. The second stage lasts about two hours in a primipara and from fifteen minutes to one hour in a multipara. _The third stage_ is the delivery of the after-birth. The after-birth sometimes called the secundines, consists of placenta, umbilical cord, and membranes. [Illustration: Fig. 42.—The head passing over the perineum. (Bumm.)] After the expulsion of the fœtus, the uterus undergoes a sudden diminution in size. It is about as large as the child’s head, and the fundus lies near the level of the umbilicus. The contractions still persist feebly, but they are practically painless, and the patient is greatly relieved, possibly sleeping. In from ten to thirty minutes, the uterus becomes smaller, harder, more globular in shape and more movable. The patient brings the voluntary muscles of the abdomen strongly into action again. The nurse presents a sterile basin and the physician sustains and slowly twists the membranes free from their final attachment and out of the uterus. When the placenta passes the vulva, a moderate sized blood clot follows it. [Illustration: Fig. 43.—Normal expulsion of the placenta like an inverted umbrella according to Schultze. (Williams.)] The uterus is now much smaller, and hard and firm in consistency, but for some hours the contractions are intermittent, and while this continues, there is risk of hæmorrhage. _General Effects._—The mother’s pulse is quickened during the contraction. The fœtal heart beats more slowly and feebly during a contraction, but quickly recovers in the interval. The amount of blood lost during labor averages from ten to sixteen ounces. The temperature may be elevated one or two degrees in a woman of moderate physique, while one with a fragile body may present the signs and symptoms of surgical shock. The chill, pallor, cold limbs and body, rapid and feeble pulse with subnormal temperature, suggest to the nurse at once the proper _treatment_. Heat, to all parts of the body, warm covers and hot milk or coffee. If hæmorrhage is present and the uterus relaxed, the nurse should immediately inject pituitrin (15 ♏︎) into the deltoid muscle and notify her attending physician. CHAPTER VIII THE MECHANISM OF NORMAL LABOR The powers of labor are primarily the uterine contractions strongly aided by the muscles of the abdomen and diaphragm. Some assistance is given by the fixation of the legs and arms and sometimes by gravity, when a sitting or standing position is maintained. The resistances are the bony pelvis and its relatively soft coverings of muscle and fascia.