In shoulder dystocia, the head of the fetus delivers but the shoulder becomes lodged against the mother’s pubic bone or sacrum. Consequently, the head pulls back slightly into the vagina. The baby cannot breathe because the birth canal puts pressure on the chest and umbilical cord. As a result, oxygen levels in the baby’s blood decrease, and there is a risk of injury or death.
Shoulder dystocia is not common, but it is more common when any of the following is present:
Difficult, long, or rapid labor
Delivery assisted by a vacuum device or forceps Operative Vaginal Delivery Operative vaginal delivery is delivery using a vacuum extractor or forceps. A vacuum extractor consists of a small cup made of a rubberlike material that is connected to a vacuum. It is inserted... read more , because the fetus’s head has not fully moved down (descended) in the pelvis
Prior delivery of a baby with shoulder dystocia
When shoulder dystocia occurs, the doctor quickly tries various techniques to free the shoulder so that the baby can be delivered vaginally. An episiotomy Delivery of the baby (an incision that widens the opening of the vagina) may be done to help with delivery.
If these techniques are unsuccessful, the baby may be pushed back into the vagina and delivered by cesarean delivery Cesarean Delivery Cesarean delivery is surgical delivery of a baby by incision through a woman’s abdomen and uterus. In the United States, up to 30% of deliveries are cesarean. Doctors use a cesarean delivery... read more .
Shoulder dystocia increases the risk of problems and of death in the newborn. The newborn's bones may be broken during delivery, and the brachial plexus Plexus Disorders Plexuses (networks of interwoven nerve fibers from different spinal nerves) may be damaged by injury, tumors, pockets of blood (hematomas), or autoimmune reactions. Pain, weakness, and loss... read more (the network of nerves that sends signals from the spinal cord to the shoulders, arms, and hands) may be injured. The pregnant woman is also more likely to have problems such as
Excessive bleeding at delivery (postpartum hemorrhage)
Tears in the area between the vaginal opening and the anus
Injury of muscles in the genital area and nerves in the groin
Separation of the pubic bones.