Birth Injuries

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Birth Injuries

Definition

A birth injury is defined by the Centers for Disease Control and Prevention (CDC) as an impairment of the neonate's (a newborn; usually less than one month old) body function or structure caused by adverse influences occurring at birth.

Description

Birth injuries can occur during any birth. In the CDC's April 1999 report on vital statistics, birth injuries were highest when mothers were 25 to 29 years of age and lowest when mothers were 40 to 54 years old. Birth injuries include:

asphyxia
shoulder dystocia
brachial plexus injury
fractures of the clavicle and humerus
fractures of the long bones
cerebral injury
cephalhematoma
facial nerve palsy

Causes and symptoms

Infants of diabetic mothers are particularly at risk for birth injuries due to macrosomia (large body size). Macrosomia is a problem in about 33% of diabetic pregnancies, even with efforts for strong glycemic control. However, when glycemic control approximates normal blood glucose levels, injury rates are reduced. Macrosomia is also a problem associated with multiparity (at least two births of a large infant by the same woman) because, with each pregnancy, the developing infant tends to be larger than its predecessor. A post-due date infant can also result in a large infant. When gestational age fetuses are large, they stretch the uterus, which can result in dysfunction during labor or delivery and increase the risk for postpartum hemorrhage. Larger infants have a 15% perinatal mortality rate versus the 4% mortality rate of appropriately sized neonates. Large infants born vaginally also have a higher than normal risk of shoulder dystocia, resulting in nerve injuries or fractured clavicle. In general, birth injuries are more likely to occur during a difficult vaginal birth, with prolonged labor, use of instrumentation such as forceps or vacuum extractor, with cephalopelvic disproportion, with fetal malpresentation, or during a Caesarian delivery. The injury may occur during labor, delivery, or neonatal resuscitation. Infants born preterm are especially at risk for birth injuries. One reason for this is the relationship between prenatal infections and preterm birth. Prenatal infection appears to play a significant role in premature delivery.

Diagnosis

Asphyxia is defined as the presence of hypoxia and acidosis. Hypoxia is a decreased level of oxygen in the tissues. Acidosis is the increased concentration of hydrogen ions in the tissues, a metabolic imbalance. Asphyxia may occur in utero, due to umbilical cord compression, placenta previa, or placental abruption (a tearing away or detachment). It can also occur during birth and postpartum. Preterm infants are especially at risk for respiratory problems. Difficulty breathing can result in prolonged fetal circulation after birth because the ductus arteriosus fails to close.

Meconium aspiration (inhalation by the newborn of its first intestinal discharges during labor and/or delivery) can also lead to impaired breathing. Deep suctioning may be required to rid the lungs of meconium. Meconium aspiration syndrome (MAS) is a serious condition in which the airway can become obstructed leading to respiratory distress, pneumonia, and even death. MAS is associated with hypoxia, pulmonary hypertension, and persistent fetal circulation. MAS occurs in only a small percentage of infants who aspirate meconium. Postdates infants (born later than the estimated date of delivery) are especially at risk for meconium aspiration, as are infants who suffered hypoxia in utero. Hypoxia leads to a relaxation of the anal sphincter muscles, allowing leakage of meconium into the amniotic (pertaining to the membrane around the fetus) fluid. MAS is eight times more likely to occur in the postdates infant than in the term infant. Meconium release is also more likely with a breech delivery because of the pressure against the buttocks. Small-for-gestational-age infants and preterm infants are a risk for asphyxia because of the increased risk of hypoxia and because their underdeveloped chest muscles lead to ineffective respiration. Infants born by cesarian section are also at risk for respiratory distress. This is because they avoid delivery through the birth canal, which causes thoracic compression and its accompanying expulsion of lung fluid.

The incidence of shoulder dystocia is increasing along with the rise in birth weight, although 40-50% of infants with shoulder dystocia have a birth weight under 4,000 grams (8.8 lbs). A large infant or cephalopelvic (size of the fetal head compared to the mother's pelvis) disproportion may not be diagnosed prior to birth. During delivery, the head can be born, but the shoulders become stuck. Danger to the mother arises with prolonged labor and delivery, the risk of cervical or vaginal tears, and postpartal hemorrhage. Fetal risks include cord compression, fractured clavicle, and brachial plexus (spinal nerve network in neckshoulder region) injury. Shoulder dystocia should be suspected with prolonged labor and in a condition called turtle sign. In turtle sign the fetal head is born then partially retracts, looking like a turtle with its head partially pulled back into its shell. Brachial plexus injury is the most common of the nerve injuries seen in neonates. Injury can arise from traction to the head and neck during a vertex (crown of the head) vaginal delivery, or during shoulder traction in a breech delivery. In Erb's palsy (paralysis of the upper arm) the C5 and C6 nerves are affected, and the arm on the affected side is limp with the affected shoulder drawn toward or past the body's median axis. The arm is internally rotated, with the elbow extended. The forearm is pronated (palms facing backwards), with wrist flexion. When eliciting the Moro reflex (primitive reflex that disappears a few months after birth), an assymetrical response is noted. The grasp reflex should remain intact. Klumpke's palsy results from an injury to the C8 and T1 nerves. Diagnosis is suspected if the hand appears paralyzed, with a limp wrist and absence of the grasp reflex. Diaphragmatic paralysis or respiratory compromise can occur with injury to other cervical nerves. Not all brachial plexus injuries occur during birth. They may have occurred earlier during the pregnancy. Care should be taken during immobilization of the affected area to avoid contractures. Treatment may be followed by physical therapy. Full recovery in seen four months for 88% of cases, with 93% resolving within two years. Periodic neurologic evaluation can help avoid long-term impairment.

A fractured clavicle may result from a difficult breech birth and also from shoulder dystocia. The clavicle should be straight, but if fractured a lump may be felt. At the time of the fracture, a cracking sound may be heard. A fracture should be suspected with decreased or lack of movement of the affected arm, swelling, skin discoloration, localized pain or tenderness, and lack of symmetry of the Moro reflex. The condition may also be asymptomatic. Injury can be confirmed by imaging. Treatment usually involves immobilizing the affected arm and shoulder for seven to 10 days.

Fractured long bones are usually caused by arm or leg rotation during a breech birth. It should be suspected with pain, swelling, and lack of movement on the affected side. The affected side may appear shorter. Imaging can confirm the diagnosis. Treatment usually involves casting the affected limb, with complete healing taking place in a month.

Cephalhematoma is subcutaneous swelling caused by accumulation of blood from ruptured blood vessels located in the back of the neonatal skull underneath the scalp. It starts forming after trauma, perhaps as a result of the use of forceps or vacuum extractor, and increases in size over the next few days after birth. The swollen area may be black and blue due to the pooled coagulated blood. Cephalhematoma may resolve in a few days or take several months. The cephalhematoma is located on one or both sides and does not cross the suture lines. It may be associated with anemia or jaundice. Usually no treatment is undertaken unless it appears infected.

Facial nerve palsy is the paralysis of a facial nerve following injury. It can occur as a result of the use of forceps, or because of pressure on the nerve due to fetal position against the mother's pelvic bones during birth or during the pregnancy. Lack of symmetry is most obvious when the infant cries. The affected side of the face looks smooth and the corner of the mouth droops. If the affected eye stays open it is necessary to use ophthalmic drops to avoid injury to the cornea. It usually resolves in a few days to weeks.

Treatment

Treatment of asphyxia involves rapid recognition of a neonate in respiratory distress. A rapid respiratory may be the first warning sign of distress. Other signs include cyanosis, sternal retractions, and lack of respiratory effort. The Apgar evaluation (a physical assessment of newborns) scores respiratory rate at one and five minutes after birth. Should the infant appear in immediate distress, intervention and/or resuscitation is begun before the one-minute time period. Some infants have periods of apnea, or temporary stoppage of breathing. For some, stimulation of the soles of the feet may be enough to remind them to continue breathing. Others may need swift intervention. Cerebral palsy (CP) is associated with lack of oxygenation in utero, during birth, or shortly afterwards. However, some studies indicate that only 9% of cerebral palsy cases are directly caused by birth asphyxia. CP is also associated with maternal infection, a significant cause of preterm birth, and low birth weight and small for gestational age infants. Newborn infections such as meningitis or encephalitis can also result in cerebral palsy. Kernicterus (a severe form of jaundice) resulting from hyperbilirubinemia (a large amount of red bile pigment, or bilirubin, in the blood) can also lead to cerebral palsy. CP is also associated with premature rupture of membranes (PROM) due to the increased risk of infection and cord compression associated with PROM.

Damage to the neonate can occur with the traction and rotation that accompanies delivery of the infant with shoulder dystocia. Asking the mother to perform the McRobert's maneuver, or the sharp flexing of her thighs against her abdomen, can widen the pelvic outlet and facilitate delivery. Cesarian delivery does not avoid all cases of brachial plexus injuries because compression can occur in utero, not just with birth.

Prognosis

The prognosis for birth injuries depends on many factors. Most of the injuries related to shoulder dystocia or fractured bones tend to heal completely, although some may require physical therapy or surgical intervention. About 10% of nerve injuries are permanent. Complications resulting from compromised oxygenation have a poorer outcome the longer the oxygen deficit has occurred. Cephalhematoma rarely requires intervention, but may when associated with anemia or hyperbilirubinemia. Degree of organ development at the time of birth is a significant factor in prognosis.

Health care team roles

Physicians, nurses, and respiratory therapists all play an important role in neonatal resuscitation. Physical therapists and nurses may have ongoing interactions with infants with cerebral palsy, or who need rehabilitation after injury from shoulder dystocia. Radiology technicians play an important role in gestational dating with ultrasound. Accurate dating and identification of small or large for gestational age infants can facilitate appropriate interventions.

Prevention

Many birth injuries cannot be prevented, as they occur in utero. Although having a member of a neonatal resuscitation team at every birth can facilitate swift intervention by specially trained individuals, it would be difficult to provide such services for all births, especially in small rural hospitals. The earlier intervention occurs, the better the prognosis. Respiratory distress is decreased with proper thermal regulation of the neonate. Drying the newborn under a radiant heater, changing the wet blankets for heated dry ones, and using a cap facilitates neonatal thermoregulation. Poor temperature control of the newborn increases respiratory effort. This is especially true in the preterm infant who has a decreased amount of brown fat. Ultrasonography assists in the diagnosis of placental problems, as well as in measuring fetal size. However, even with such technology, not all potential problems will be diagnosed prior to birth. Careful fetal monitoring during labor can often recognize fetal distress before permanent damage takes place. Close monitoring of the postdates fetus can decrease risk of placental insufficiency and cord compression due to insufficient amniotic fluid volume. The use of corticosteroids given to the mother before the delivery of a preterm infant can also decrease the risk of cerebral palsy.

KEY TERMS

Adduction— The limb is drawn in towards the body.

Apgar score— The results of an evaluation of a newborn's physical status, including heart rate, respiratory effort, muscle tone, response to stimulation, and color of skin.

Macrosomia— A condition in which the neonate is large for gestational age with a high body weight. The condition is particularly associated with infants of diabetic mothers, especially if the diabetes is not well controlled. The circulating hyperglycemia encourages rapid growth and weight gain.

Meconium aspiration— When a newborn inhales its first fecal discharges during labor or delivery.

Pronation— The palm of the hand faces backwards.