20.2 Preterm Birth

Preterm birth is defined as infants born alive before 37 weeks of pregnancy. There are sub-categories of preterm and term birth based on gestational age^[1]:

• Extremely preterm: Less than 28 weeks’ gestation
• Very preterm: 28 weeks to less than 32 weeks’ gestation
• Moderate to late preterm: 32 to 37 weeks’ gestation
• Early term: 37 through 38 weeks’ gestation
• Full term: 39 through 40 weeks’ gestation

In the United States, preterm births affect 1 out of 10 infants. Differences continue to exist for several ethnic groups, resulting in even higher preterm birth rates. For example, preterm birth rates among Black women is 14.6%. Significant growth and development occurs in the final weeks of pregnancy, especially in the fetal lungs, brain, and liver, so infants born prematurely (especially before 32 weeks) have higher rates of morbidity and mortality. In 2022, preterm birth and low-birth weight accounted for about 14.0% of infant deaths. Preterm infants who survive may have long-term respiratory problems, feeding difficulties, cerebral palsy, developmental delays, vision problems, and hearing problems. Preterm births can also take an emotional toll and be a financial burden for families.^[2]

Risk Factors for Preterm Birth

Infants may be born preterm because of spontaneous preterm labor or because of a medical indication requiring induction of labor or a caesarean delivery.^[3] Modifiable and nonmodifiable risk factors for preterm birth are summarized in Table 20.2.

Table 20.2. Modifiable and Nonmodifiable Risk Factors for Preterm Birth^[4],[5]

Signs of Prematurity

Newborns who are born prematurely exhibit several common signs, including the following^[6]:

• Small body size with a large head in proportion to the body
• Facial features that are sharper and less rounded than a full-term infant’s features due to decreased fat storage
• Lanugo (fine hair that covers much of the body)
• Low body temperature, especially right after birth in the delivery room, related to poor thermoregulation
• Respiratory distress
• Feeding problems

See Figure 20.1^[7] for an image of a preterm infant in a neonatal intensive care setting.

Complications of Prematurity

In general, the earlier a premature infant is born, the higher the risk of complications that may occur. Some complications occur soon after birth, whereas others may not appear until the infant ages.

In the first few weeks after birth, complications of premature birth may include the following^[8]:

• Breathing problems: A premature infant’s lungs may not be fully developed or they may lack a substance called surfactant that prevents the alveoli from collapsing, commonly causing respiratory distress syndrome (RDS). Undeveloped lungs can also cause persistent pulmonary hypertension of the newborn (PPHN). If a newborn with respiratory distress requires mechanical ventilation or long-term oxygen therapy, inflammation and damage can occur to their undeveloped lungs, causing a chronic disorder called bronchopulmonary dysplasia.^[9] Another type of respiratory complication in premature infants is apnea of prematurity (AOP). Premature infants are also at higher risk of sudden infant death syndrome (SIDS). These conditions are further discussed in the following subsection on “Respiratory Problems.”
• Cardiovascular problems: Premature babies may have patent ductus arteriosus (PDA) and hypotension. The ductus arteriosus is a normal part of fetal circulation that includes an opening between the aorta and the pulmonary artery. This opening typically closes on its own after birth, but if it doesn’t close, the infant is diagnosed with PDA. PDA can cause symptoms of heart failure. Premature infants may also experience hypotension requiring administration of intravascular fluids and medications. Read more about PDA and other congenital heart defects in the “Congenital Heart Defects” chapter.
• Gastrointestinal problems: Premature infants are more likely to have digestive systems that aren’t fully developed, resulting in complications such as necrotizing enterocolitis (NEC). NEC refers to injury to the cells lining the bowel. Premature babies who receive only breast milk have a much lower risk of getting NEC. This condition is further discussed in the following subsection on “Gastrointestinal Problems” in this chapter.
• Neurological problems: The earlier a premature infant is born, the greater their risk of bleeding in the brain, called intraventricular hemorrhage. Most hemorrhages are mild and resolve with little short-term impact, but some infants have larger amounts of brain bleeding that causes permanent brain injury. Premature infants are also at higher risk of neonatal seizures. These conditions are further discussed in the following subsection on “Neurological Problems” in this chapter.
• Impaired thermoregulation: Premature babies don’t have as much brown fat (i.e., a type of fat that breaks down glucose and fat molecules to create heat and maintain body temperature). A preterm infant also may use up all of the energy gained from feedings just to stay warm. They also have less glycogen stored in their liver, resulting in less energy stored to make enough heat to counter what is lost through the surface of their bodies, especially if they are hypoglycemic. Furthermore, if their body temperature drops too low, hypothermia can result in breathing problems. Small premature babies typically need extra heat from an infant warmer or an incubator to help maintain their body temperature and prevent hypoglycemia.
• Hematology problems: Premature infants are at risk for anemia, hyperbilirubinemia, and newborn jaundice. All newborns have a slow decrease in red blood cell count during the first months of life, but that drop may be greater in premature babies. Read more information about hyperbilirubinemia in the “Common Complications During the Neonatal Period” section of the “Healthy Newborn Care” chapter.
• Metabolism problems: Premature babies often have problems with metabolism, meaning converting food into energy. They have problems converting glycogen stored in the liver and muscles into more usable, active forms of blood glucose.
• Immune system problems: It is common for premature infants to have immune systems that aren’t fully developed, increasing their risk of infection and sepsis.

Over the long term, premature infants may develop chronic conditions such as the following^[10]:

• Cerebral palsy: Cerebral palsy may result from hypoxia, infection, or brain injury during pregnancy or delivery. This group of disorders can cause problems with movement, muscle tone, or posture. Read more about cerebral palsy in the “Other Musculoskeletal Disorders” section of the “Musculoskeletal System Alterations” chapter of Open RN Health Alterations.
• Developmental delays and learning disabilities: Premature babies are more likely to lag behind full-term babies on achieving developmental milestones and may experience learning disabilities. Read more information about developmental delays in the “Nursing and Medical Care of the Developing Child” section of the “Nursing Care for Infancy Through Adolescence” chapter.
• Vision problems: Premature infants may develop an eye disease called retinopathy of prematurity, where blood vessels swell and overgrow in the retina. Sometimes these overgrown vessels slowly scar the retina and pull it out of place, called retinal detachment. Without treatment, retinal detachment can harm vision and cause blindness.
• Hearing problems: Premature babies have a higher risk of hearing loss. All infants should have a hearing screen before they go home from the hospital.
• Dental problems: Preterm babies may be more likely than full-term babies to have defects with the hard outer covering of the teeth, called enamel. Infants born very premature or extremely premature may also have delayed tooth development.
• Mental health disorders and other health conditions: Infants who were born prematurely may be at greater risk for mental health and behavioral disorders. Premature infants are more likely to have long-term health issues, asthma, and feeding problems.

Respiratory Problems

Respiratory Distress Syndrome

Respiratory distress syndrome (RDS) is a common breathing disorder commonly caused by lack of pulmonary surfactant in the lungs. Surfactant is essential for adequate oxygen exchange by keeping the alveoli open and preventing them from collapsing during exhalation. RDS is common in preterm infants, especially those born before 34 weeks of gestation.^[11]

Respiratory distress can also be caused by meconium aspiration syndrome, although this condition is more likely to occur in post-term births or in infants who are small for gestational age. Read more about meconium aspiration syndrome under the “Post-Term Birth” section.

Infants with RDS experience rapid, shallow breathing; retractions (visible pulling in of the chest or ribs during breathing); and grunting sounds during exhalation. They may exhibit signs of  central cyanosis (with a bluish tint around the mouth or in the nailbeds). Note that central cyanosis is different from acrocyanosis (bluish discoloration of the hands and feet) that may occur in healthy newborns. RDS is diagnosed with a chest X-ray that shows low lung volumes and classic diffuse “ground glass” appearance, as illustrated in Figure 20.2.^{[12],[13],[14]}

Medical treatment for infants with RDS includes providing supplemental oxygen, often with continuous positive airway pressure (CPAP). Some infants with severe RDS require intubation and mechanical ventilation to maintain adequate oxygenation. Surfactant is administered by a health care provider or respiratory therapist directly into the newborn’s lungs through an endotracheal tube (a thin tube inserted into the airway). The specific dosage is determined by the health care provider based on the infant’s weight and severity of RDS. Surfactant therapy is usually initiated shortly after birth of a premature infant, especially if the infant is showing signs of RDS. The infant’s body temperature is also closely monitored and kept within normal range to help conserve energy and support respiratory function. With proper medical care, the majority of infants with RDS recover over time as their lungs mature and their natural production of surfactant increases.^[15]

If a mother is at risk of premature birth before Week 34 of pregnancy, treatment for RDS can begin before birth with administration of antenatal corticosteroids (ACS), such as betamethasone or dexamethasone. ACS induce fetal pulmonary beta-receptors, resulting in ѕսrfаctaոt release and absorption of alveolar fluid. However, for these changes to occur, the fetal lungs must reach a developmental stage that is biologically responsive to ϲοrtiϲοѕterοidѕ. ΑCЅ is generally administered during pregnancies of 22 weeks to 33 weeks +6 days’ gestation.^[16]

Persistent Pulmonary Hypertension of the Newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a serious cardiovascular condition that occurs when a newborn’s pulmonary blood vessels don’t open properly after childbirth, leading to severe hypoxemia. During normal transition after birth, several events occur simultaneously that result in a smooth transition to extrauterine life. Pulmonary arterial pressure falls dramatically following the first breath, accompanied by increased pulmonary blood flow when the umbilical cord is clamped. Between 7% and 10% of newborns with PPHN die from complications. Of those that survive, 25% experience chronic conditions from lack of oxygen reaching their brain, such as developmental delays, learning disabilities and hearing problems.^[17]

There are several risk factors for PPHN, including the following^[18]:

• Respiratory distress syndrome (RDS) in premature infants who don’t have fully developed lungs
• Meconium aspiration syndrome
• Infection, including pneumonia and sepsis
• Birth asphyxia (lack of oxygen before or during birth)
• Diaphragmatic hernia (a hole in an infant’s diaphragm that allows contents of their abdomen to intrude in their chest)
• Congenital heart and lung abnormalities, such as lungs that are smaller than they should be or a blocked heart valve
• Certain maternal medications taken during late pregnancy, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and selective serotonin receptor inhibitors (SSRIs), increase the risk for PPHN

Treatment of PPHN may include the following options, based on the severity of the condition^[19]:

• 100% supplemental oxygen through nasal cannula or a mask
• Intubation and mechanical ventilation
• Intravenous antihypertensive medications
• Nitric oxide, a gas that helps dilate pulmonary blood vessels and improve blood flow
• Extracorporeal membrane oxygenation (ECMO), a life support therapy that pumps blood from a large vein into the ECMO machine, where carbon dioxide is removed, and oxygen is added to the blood and then the oxygenated blood is pumped back into the body through another large vein.

Most cases of PPHN resolve within one to two weeks, although some take months to fully recover.^[20]

Bronchopulmonary Dysplasia

Premature newborns with RDS or other respiratory complications who require long-term oxygen therapy or mechanical ventilation may experience damage to their undeveloped lung tissue, causing a chronic lung disorder called bronchopulmonary dysplasia (BPD). Most cases of BPD occur in newborns born more than 10 weeks early, weigh less than two pounds at birth, and have breathing problems. BPD can also be caused by other conditions, such as maternal smoking or illicit drug use, preeclampsia, or chorioamnionitis. Bronchopulmonary dysplasia is associated with high morbidity and mortality rates. There is no specific cure for BPD, but treatment focuses on minimizing further lung damage and providing support for the infant’s lungs, allowing them to heal and grow. Medications may include the following^[21]:

• Diuretics: To decrease the amount of fluid in and around the alveoli.
• Bronchodilators: To widen the airways and improve airflow.
• Inhaled corticosteroids: To reduce and/or prevent inflammation within the lungs and decrease the amount of mucus that is produced.
• Monthly injections of monoclonal antibodies: To prevent respiratory syncytial virus (RSV).

Infants with severe disease may require oxygen therapy for several months, often in association with CPAP or bilevel positive airway pressure (BiPAP) to keep the airways open. Symptoms often improve by two or three years of age but may cause chronic lung problems later in life such as asthma or reactive airway disease.^[22]

Apnea of Prematurity

Almost all neonates born before 28 weeks’ gestation have apnea of prematurity. In contrast, less than 10 percent of preterm infants born after 34 weeks experience this condition. The immature control of breathing stems from three areas, including neuromuscular, brainstem centers, and peripheral chemoreceptors. See Figure 20.3^[23] for an illustration of the causes of apnea of prematurity. These three areas, when ineffective, can result in apnea and periodic breathing that ultimately leads to bradycardia, desaturation, and hypoxia. Immature breathing control in the brain stem and neuromuscular control of the airway cause apnea episodes of greater than 20 seconds. Note that this condition is different from the normal periodic breathing of healthy newborns who have rapid breathing for a few seconds, followed by a pause for up to ten seconds, and then a resumption of breaths.

Transient Tachypnea of the Newborn

Transient tachypnea of the newborn (TTN) is caused by delayed clearance of fetal lung fluid after birth. TTN can affect both preterm and term infants. Normally, during vaginal delivery, the pressure exerted on the newborn’s chest helps expel excess lung fluid. However, during cesarean deliveries or rapid labor and vaginal deliveries, this fluid clearance process may be delayed. Maternal diabetes also increases the risk of TTN. Infants with TTN experience tachypnea, expiratory grunting, and mild retractions. Cyanosis may or may not be present. Treatment involves supportive respiratory therapy, including supplemental oxygen. In most cases, infants with TTN recover within a few days as their lung fluid is gradually absorbed and their breathing stabilizes.

Sudden Infant Death Syndrome (SIDS)

Sudden infant death syndrome (SIDS) is the unexplained death of an infant who seems to be healthy, often during their sleep. The cause of SIDS is unknown, but it may be caused by problems in the area of an infant’s brain that controls breathing and waking up from sleep. SIDS can happen to any infant, but premature infants and those with low-birth weight are at higher risk. Exposure to secondhand smoke and a recent upper respiratory infection also increase the risk for SIDS. Other risk factors for SIDS include the following^[24]:

• Sleeping on their stomach or side: Babies placed in these positions to sleep may have more trouble breathing than those placed on their backs, especially premature infants.
• Sleeping on a soft surface: Lying face down on a fluffy comforter, a soft mattress or a waterbed can block an infant’s airway.
• Sharing a bed: The risk of SIDS rises if a baby sleeps in the same bed with parents, siblings, or pets, but sleeping in a separate bed in the same room with parents lowers the risk of SIDS.
• Overheating: Being too warm while sleeping can increase a baby’s risk of SIDS.

Nurses teach parents tips to prevent SIDS, including the following^[25]:

• Place the baby to sleep on their back in their first year of life.
• Use a firm, flat mattress in the crib.
• Do not leave fluffy pillows, blankets, or stuffed animals in the crib.
• Try sleep sacks or multiple layers to keep the baby warm instead of blankets. Do not allow the baby to become overheated.
• Allow the baby to sleep in their own bed in the room with you for at least six months.
• Breastfeeding for at least six months reduces the risk of SIDS.
• Offer a pacifier at naptime or bedtime, but don’t force it. If it falls out while the baby is sleeping, do not put it back in their mouth.
• Keep the baby’s vaccinations up-to-date, especially to prevent respiratory illnesses that increase the risk of SIDS.

Gastrointestinal Problems

Necrotizing Enterocolitis

Premature infants are at higher risk for necrotizing enterocolitis (NEC), with high infant morbidity and mortality rates. NEC refers to death of tissue in the intestine. The exact cause of this disorder is unknown, but it may be caused by decreased blood flow to the bowel or undeveloped immune response to factors such as bacteria.^[26]

Signs of NEC include an abrupt change in feeding tolerance with abdominal distention; diarrhea; blood in the stool; lack of energy; unstable body temperature; unstable breathing, heart rate, or blood pressure; and vomiting. NEC is diagnosed on abdominal X-ray showing intramural gas in the lining of the intestines.^[27] See Figure 20.4^[28] for an image of an abdominal X-ray of an infant with NEC with intramural air bubbles in the intestinal wall lining from gas produced by bacteria.

When NEC is suspected, the infant is made NPO, and total parenteral nutrition (TPN) is typically started, along with intravenous fluids. A nasogastric (NG) tube may be inserted to remove gas from the bowel. Antibiotic therapy is prescribed to limit the progression of the disease, with frequent abdominal X-rays performed to monitor for the progression of NEC. In severe cases of NEC, surgical intervention may be required to remove dead bowel tissue.^[29],[30]

Neurological Problems

Preterm infants are at risk for neurological conditions, such as intraventricular hemorrhage and neonatal seizures.

Intraventricular Hemorrhage

Very preterm and extremely preterm infants are at risk for a serious condition called intraventricular hemorrhage (IVH), especially those weighing less than three pounds, five ounces. Immature brain blood vessels are fragile and easily break, causing bleeding into the ventricles (spaces) and fluid-filled areas of the brain, often within the first three days of life. Other risk factors of IVH include multiple gestation, difficult delivery, inflammation, and respiratory or cardiopulmonary instability.^[31],[32]

Signs of IVH are apnea, decreased muscle tone and reflexes, excessive sleep, lethargy, and a weak suck. However, no signs of IVH may be present, so a head ultrasound is typically performed for all preterm infants born before 30 weeks of gestation. An initial ultrasound is performed in the first two weeks of life and then repeated near their corrected gestational age of 40 weeks.^[33]

IVH is often described in four grades, depending on the amount of bleeding^[34]:

• Grade one: Bleeding occurs just in a small area of the ventricles.
• Grade two: Bleeding also occurs inside the ventricles.
• Grade three: Ventricles are enlarged by the blood.
• Grade four: Bleeding also occurs in the brain tissues around the ventricles.

No treatment exists to stop intraventricular bleeding, but supportive care is provided, such as blood transfusions for infants who develop anemia as a result of the bleeding. Other treatment depends upon the grade of bleeding. In severe cases where hydrocephalus (excessive cerebrospinal fluid) occurs as a result of increased intracranial pressure, surgical placement of a shunt or drain may be performed to relieve pressure in the brain. The prognosis of infants with IVH is based on the severity of the bleeding.^[35],[36]

The risk of IVH may be reduced by administering antenatal corticosteroids to mothers who are at risk of premature delivery.^[37]

Neonatal Seizures

Premature infants are at risk for seizures due to their immature brain. Seizures may also occur due to conditions such as hypoxic-ischemic encephalopathy (lack of oxygen or blood flow to the brain), intracranial bleeding, cerebrovascular accident, infection, hypoglycemia, electrolyte imbalances, metabolic disorders, withdrawal from maternal substance use, or congenital birth defects. Many neonatal seizures occur without clinical signs and are detectable only on electroencephalogram (EEG). Signs of a neonatal seizure are subtle and may include fine movements, such as lip smacking, or twitching of one area, such as an eye or a hand. Early identification of seizures, followed by early treatment, helps prevent long-term consequences, such as neurodevelopmental delays. Medications such as anticonvulsants (phenobarbital, phenytoin, levetiracetam), benzodiazepines, and corticosteroids may be prescribed to treat neonatal seizures.^{[38],[39], [40]}

Nursing Care of the Preterm Infant

Nursing care of preterm infants requires specialized knowledge and a compassionate, skilled approach to provide optimal care and support for the infant and their family. Preterm infants born before 37 weeks of gestation typically require intensive care in a neonatal intensive care unit (NICU). Nursing care for preterm infants focuses on medical needs of the infant, as well as emotional needs of the parents. Providing family-centered care that fosters communication, education, and involvement helps support the well-being of both the preterm infant and their family. Nursing care typically includes the following components:

• Respiratory Support: Monitor respiratory status closely. Maintain a stable oxygen saturation level to avoid complications like retinopathy of prematurity (ROP). Preterm infants often have underdeveloped lungs and require oxygen therapy, continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP), or mechanical ventilation.
• Temperature Regulation: Preterm infants have limited ability to regulate their body temperature. Keep them warm through the use of incubators, radiant warmers, and warm blankets. Continuously monitor temperature to prevent hypothermia or hyperthermia.
• Feeding and Glucose Management: Enteral feedings are initiated gradually, usually starting with breast milk or formula through a feeding tube. Assess for signs of feeding intolerance and adjust feeding rates accordingly. Monitor blood glucose per agency protocol or provider order.
• Infection Prevention: Preterm infants are at high risk of infection. Strictly adhere to infection control practices, including hand hygiene and proper sterile procedures, to minimize the risk of infections in these vulnerable infants. Encourage parents and visitors to follow infection prevention protocols.
• Skin Care: Preterm infant skin is delicate and sensitive. Provide gentle skin care to prevent skin breakdown and use appropriate moisture barriers to prevent diaper rash. Avoid excessive handling and use soft linens to prevent skin irritation.
• Neurodevelopmental Support: Implement developmental care practices that reduce stress, promote sleep (and growth), and support brain development. Encourage skin-to-skin contact with parents, which has been shown to benefit preterm infants’ well-being.
• Monitor for Complications: Monitor weight gain and growth and assess for signs of common preterm complications such as respiratory distress syndrome, intraventricular hemorrhage, neonatal seizures, necrotizing enterocolitis, and retinopathy of prematurity.
• Provide Health Teaching and Emotional Support to Parents:  Involve parents in care decisions and provide health teaching about their infant’s condition, care plan, and progress. Offer emotional support and encourage them to ask questions and verbalize feelings. Provide a safe, soothing space where they can bond with their baby.
• Administer Medications: Administer prescribed medications accurately and monitor for potential side effects or adverse reactions. Ensure safe and appropriate dosage calculations for preterm infants’ size and weight to prevent medication errors.
• Collaborate with the Health Care Team: Work collaboratively with neonatologists, respiratory therapists, occupational therapists, and other healthcare professionals to provide comprehensive care. Advocate for a coordinated care plan.