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Spontaneous delivery of the vertex-presenting infant is divided into three phases: delivery of the head, delivery of the shoulders, and delivery of the body and legs.

Delivery of the Head

Anticipate delivery when the presenting part reaches the pelvic floor. With each contraction, the perineum bulges increasingly and the vulvovaginal opening becomes more and more dilated by the fetal head. Just before delivery, crowning occurs, which is when the head is visible at the vaginal introitus and the widest portion, or the biparietal diameter of the head, distends the vulva.

Gentle, gradual, controlled delivery is desirable. Avoid explosive delivery of the head. Once the fetal head distends the vaginal introitus to 5 cm or more during a contraction, place the palm of one hand over the occipital area and provide gentle pressure to control delivery of the head. With the other hand, preferably draped with a sterile towel to protect it from the anus, exert forward pressure …