In a vertex presentation, left-occipito-anterior position, while the occiput passes under the symphysis and appears at the distending vaginal outlet, the face passes down the posterior wall and along the floor of the pelvis. As pressure is exerted by the rapidly succeeding contractions, the head pivots about the pubis, thus extending the neck and pushing the face farther downward and forward. After emergence of the back and top of the head below the symphysis, the forehead appears over the posterior margin of the vagina, then the brow, eyes, nose, mouth and chin in turn, and the entire head is born. (Fig. 68.) The baby’s head then drops forward, in relation to its own body, with its face toward the mother’s rectum and the occiput in front of the pubis, but soon the occiput rotates toward the mother’s left side, resuming the relation that it bore to the inner aspect of her pelvis before expulsion. The undelivered shoulders are now antero-posterior, one under the pubis and the other resting on the perineum. (Fig. 69.) The lower, or posterior shoulder is born first (Fig. 70), followed quickly by the anterior shoulder and the rest of the body, and the amniotic fluid which was behind the child’s body. Thus is the second stage completed. [Illustration: FIG. 72.—Longitudinal section through uterus showing thinness of uterine wall before expulsion of fetus, contrasting sharply with thickened wall in Fig. 73. (From photograph of specimen, to which twin placentæ are still adherent in upper segment, in the obstetrical laboratory, Johns Hopkins Hospital.) ] =Third Stage.= The third stage, sometimes termed the placental stage, is that period following the birth of the child, during which the placenta is delivered. For a few moments after the baby is born the tired mother lies quietly and free from pain, as there is a temporary cessation of the uterine contractions, and she often sleeps as a result of the anesthetic given during the second stage. [Illustration: FIG. 73.—Longitudinal section through uterus, immediately after labor, showing marked thickening of wall as a result of muscular contraction. (From photograph of specimen in the obstetrical laboratory, Johns Hopkins Hospital.) ]