The National Vital Statistics Report defines birth injury as “an impairment of the neonate’s body function or structure due to an adverse event that occurs at birth.” Recent studies estimate that birth trauma occurs in 29 per 1,000 live births in the United States. These are injuries not related to any birth defects or genetic factors. In 2020, there were 3,605,201 live births in the US, down 4% from 2019. That equates to approximately 105,000 birth injuries per year.
The majority of injuries to the fetus or newborn involve the head, face, neck and brain because most babies are positioned head-down in the uterus or birth canal. Trauma to the head can occur from the normal birth process when soft tissues press against the bony maternal pelvis or from external devices such as when a vacuum extractor or forceps are utilized. Neck trauma can occur from stretching of nerves in the neck, brachial plexus injury, during a difficult delivery or can cause trauma to the cervical spine. Skeletal trauma, such as collar bone fractures, occur in up to 15 per 1,000 live births. A humeral fracture is the most common skeletal injury to occur in association with brachial plexus injuries. Brain injuries can occur when there is a lack of oxygen issue that presents during the labor or birthing process. We will limit this discussion of this blog post to newborn head trauma.
There are several risk factors for increased incidence of newborn head trauma. The most significant risk factor is prematurity at the time of birth. Prematurity is defined as birth at less than 37 completed weeks of gestation, which remains at approximately 10% in the United States. The preterm fetus has fragile blood vessels throughout its body and less mature brains than full-term babies making them more prone to both external head trauma as well as brain injury during birth.
As mentioned above, the normal birthing process can cause swelling and bruising to the baby’s head and even damage to the brain in some circumstances. Macrosomia is defined as a fetal weight of >4,000 grams or 8 pounds 13 ounces. A bigger baby generally, but not always, has a larger head, making their passage through the birth canal more difficult. Cephalopelvic disproportion, or CPD, occurs when the fetal head is bigger than, or does not fit correctly, into the maternal pelvis, making the passage difficult or impossible. This often leads to a lengthy labor and/or delivery process which can increase the risk of head trauma. A rapid or prolonged delivery can also increase the risk of head trauma to the baby as there are increased forces against the mother’s bony pelvis as the baby tries to navigate its way through the birth canal. Operative vaginal delivery, the use of vacuum extractor or forceps assistance, can also increase the risk of head trauma to the newborn, both externally and internally. In 2017, 3.1% of all deliveries in the United States were accomplished via operative vaginal delivery approach. Forcep deliveries accounted to 0.5% of vaginal births and vacuum assisted deliveries accounted for 2.6% of vaginal births. Trauma to the baby’s head can also occur when there are unknown or unidentified causes.
Caput succedaneum is common scalp swelling in newborns. You may have heard this called “cone head.” It is caused by subcutaneous swelling and edema of the scalp between the skin and periosteum, the fibrous layer covering the skull, due to local venous congestion from the pressure of the presenting part of the head in the birth canal. Because it is above the periosteum, the swelling can cross suture lines and may shift as the baby is repositioned following delivery. No interventions are required, and the swelling usually subsides over the first few days after birth.
A cephalohematoma is a localized collection of blood below the periosteum resulting from the rupture of blood vessels traveling from the skull to the periosteum. This scalp swelling does not cross suture lines and is often only on one side of the head. It is more common in deliveries where vacuum or forceps were utilized. It usually resolves spontaneously in 2 weeks to 3 months without any interventions, but complications such as calcification of the hematoma, deformities of the skull, infection of the hematoma and osteomyelitis of the skull can occur.
Skull fractures are most often the result of an instrumented vaginal delivery. They may be linear or depresses and are usually asymptomatic unless associated with an intracranial injury. Plain x-rays of the skull usually confirm the diagnosis, but a head CT or MRI of the brain may be needed if there is any suspicion of neurological damage.
A subgaleal hemorrhage is a collection of blood in the loose tissue space between the galea and periosteum of the skull. The injury occurs when there is traction pulling the scalp away from the stationary bony skull, resulting in shearing or tearing of the bridging blood vessels. A difficult vaginal delivery resulting in the use of forceps or vacuum is the most common scenario associated with subgaleal hemorrhage. It has been estimated to occur in 4 of 10,000 spontaneous vaginal deliveries and 59 of 10,000 vacuum-assisted deliveries. There is the potential for massive and catastrophic hemorrhage in this type of bleed as the area attaches at the frontal bone and extends all the way back to the nape of the neck. It can lead to acute hypovolemic shock, multi-organ failure, and even death. Rapid recognition of this condition is essential.