pediatrics
Preterm Infants
Complications of Prematurity
The incidence and severity of complications of prematurity increase with decreasing gestational age and birthweight. Some complications (eg, necrotizing enterocolitis, retinopathy of prematurity, bronchopulmonary dysplasia, intraventricular hemorrhage) are uncommon in late preterm infants. Most complications relate to dysfunction of immature organ systems. In some cases, complications resolve completely; in others, there is residual organ dysfunction. CNS complications include Poor sucking and swallowing reflexes Apnea of Prematurity None Intracranial Hemorrhage in Neonates None Childhood Development None Infants born before 34 weeks of gestation have inadequate coordination of sucking and swallowing reflexes and need to be fed intravenously or by gavage. When to begin oral feedings is based on the infant's display of readiness cues for feeding, physiologic stability, and lack of need for advanced respiratory support (eg, ventilator, high-flow nasal catheters, CPAP). Evaluation for signs of feeding readiness does not begin until after 32 weeks postmenstrual age. Immaturity of the respiratory center in the brain stem results in apneic spells ( Pathophysiology ). Apnea may also result from hypopharyngeal obstruction alone ( The periventricular germinal matrix (a highly cellular mass of embryonic cells that lies over the caudate nucleus on the lateral wall of the lateral ventricles of a fetus) is prone to hemorrhage, which may extend into the cerebral ventricles ( Intraventricular hemorrhage and/or intraparenchymal hemorrhage ). Infarction of the periventricular white matter (periventricular leukomalacia) may also occur for reasons that are incompletely understood. Hypotension, inadequate or unstable brain perfusion, and blood pressure peaks (as when fluid or colloid is given rapidly IV) may contribute to cerebral infarction or hemorrhage. Periventricular white matter injury is a major risk factor for Preterm infants, particularly those with a history of Neonatal Sepsis , Ocular complications include Retinopathy of Prematurity (ROP) Myopia and/or Strabismus None Retinal vascularization is not complete until near term. Preterm delivery and the therapies needed to treat it (eg, supplemental oxygen) may interfere with the normal vascularization process, resulting in abnormal vessel development and sometimes defects in vision including blindness. Incidence of ROP is inversely proportional to gestational age. Disease usually manifests between 32 weeks and 34 weeks of gestational age. Incidence of myopia and strabismus increases independently of ROP. Infectious complications include Neonatal Sepsis None Neonatal Bacterial Meningitis None Sepsis or meningitis is about 4 times more likely in the preterm infant, occurring in almost 25% of very low-birthweight infants. The increased likelihood results from indwelling intravascular catheters and endotracheal tubes, areas of skin breakdown, and markedly reduced serum immunoglobulin levels (see Neonatal Immunologic Function ). Pulmonary complications include Respiratory Distress Syndrome in Neonates None Respiratory insufficiency of prematurity Chronic lung disease ( Bronchopulmonary Dysplasia (BPD) ) Surfactant production is often inadequate to prevent alveolar collapse and atelectasis, which result in respiratory distress syndrome (hyaline membrane disease). Many other factors can contribute to respiratory distress in the first week of life. Regardless of the cause, many extremely preterm and very preterm infants have persistent respiratory distress and an ongoing need for respiratory support. Some infants are successfully weaned off support over a few weeks; others develop chronic lung disease (bronchopulmonary dysplasia) with need for prolonged respiratory support using a high-flow nasal cannula, Continuous Positive Airway Pressure (CPAP) (CPAP) or other noninvasive ventilatory assistance, or prophylaxis for Prevention is important for infants with chronic lung disease. In addition, the American College of Obstetricians and Gynecologists recommends maternal RSV vaccination between 32 and 36 6/7 weeks of gestation, if birth is expected during the RSV season, to prevent RSV lower respiratory tract infection in infants ( Complications references ). However, it is uncertain whether maternal RSV vaccination will benefit many preterm infants because timing of birth may not allow timely administration of the vaccine. Gastrointestinal complications include Feeding intolerance, with increased risk of aspiration Necrotizing enterocolitis Feeding intolerance is extremely common because preterm infants have a small stomach, immature sucking and swallowing reflexes, and inadequate gastric and intestinal motility. These factors hinder the ability to tolerate both oral and nasogastric feedings and create a risk of aspiration. Feeding tolerance usually increases over time. Necrotizing Enterocolitis usually manifests with bloody stool, feeding intolerance, and a distended, tender abdomen. Necrotizing enterocolitis is the most common surgical emergency in the preterm infant. Complications of neonatal necrotizing enterocolitis include bowel perforation with pneumoperitoneum, intra-abdominal abscess formation, stricture formation, short bowel syndrome, septicemia, and death. The overall incidence of structural congenital heart defects among preterm infants is low. The most common cardiac complication is Patent Ductus Arteriosus (PDA) (PDA) 29 weeks of gestation at birth who have Respiratory Distress Syndrome in Neonates have a 65 to 88% risk of a symptomatic PDA. If infants are ≥ 30 weeks of gestation at birth, the ductus closes spontaneously in 98% by the time of hospital discharge. Renal complications include Metabolic Acidosis None Growth failure Renal function is limited, so the concentrating and diluting limits of urine are decreased. Late metabolic acidosis and growth failure may result from the immature kidneys’ inability to excrete fixed acids, which accumulate with high-protein formula feedings and as a result of bone growth. Sodium and bicarbonate are lost in the urine. Metabolic complications include Hypoglycemia and hyperglycemia Hyperbilirubinemia Metabolic bone disease (osteopenia of prematurity) Congenital hypothyroidism Neonatal Hypoglycemia and Neonatal Hyperbilirubinemia occurs more commonly in the preterm as compared to the term infant, and Metabolic bone diseasewith osteopenia is common, particularly in extremely preterm infants. It is caused by inadequate intake of calcium, phosphorus, andvitamin Dand is exacerbated by administration of diuretics and corticosteroids. Breast milk also has insufficient calcium and phosphorus and must be fortified. Supplementalvitamin Dis necessary to optimize intestinal absorption of calcium and control urinary excretion. Hypothyroidism in Infants and Children , The most common temperature regulation complication is Hypothermia in Neonates None Preterm infants have an exceptionally large body surface area to volume ratio. Therefore, when exposed to temperatures below the neutral thermal environment, they rapidly lose heat and have difficulty maintaining body temperature. The neutral thermal environment is the environmental temperature at which metabolic demands (and thus calorie expenditure) to maintain normal body temperature (36.5 to 37.5° C rectal) are lowest. 1.American College of Obstetricians and Gynecologists: Practice Advisory: Maternal Respiratory Syncytial Virus Vaccination. 2023. Accessed October 6, 2023. 2.Wassner AJ, Brown RS: Hypothyroidism in the newborn period.Curr Opin Endocrinol Diabetes Obes20(5):449–454, 2013. doi: 10.1097/01.med.0000433063.78799.c2 