Term newborns are susceptible to various illnesses and injuries. In many instances, clinical manifestations of these disorders are extensions of pathological effects already incurred by the fetus. A common example is the newborn who is depressed and acidotic because of intrapartum septicemia. Susceptibility varies depending upon gestational age, and those more common in term newborns are considered here. Those more frequent in preterm neonates are discussed in Chapter 34. Specific disorders that are the direct consequence of maternal diseases are discussed in pertinent chapters.
At the time of delivery, the newborn must convert rapidly to air breathing as described in Chapter 32 (p. 586). With inspiration, alveoli expand, lung fluid is cleared, and surfactant prevents alveolar collapse. Interference with these functions can create respiratory insufficiency. The neonate demonstrates hypoxemia and compensatory tachypnea, nasal flaring, chest wall retractions, and grunting. In preterm neonates, this is often caused by lung immaturity and insufficient surfactant—respiratory distress syndrome (RDS), which is discussed in Chapter 34 (p. 615).
As fetuses approach term, surfactant deficiency as a cause of respiratory distress diminishes. The leading causes in term newborns are transient tachypnea of the newborn (TTN), meconium aspiration syndrome, pneumonia, and pneumothorax. Less common etiologies are RDS, persistent pulmonary hypertension, acid/base disturbances, central nervous system (CNS) insults, and congenital chest, respiratory tract, CNS, or cardiac anomalies (Alhassen, 2021).
Following birth, successful neonatal transition to air breathing may be delayed. With longer delays, evaluations to identify the cause of respiratory distress are warranted. The initial neonatal evaluation includes chest radiographs. Complete blood count or C-reactive protein levels and blood cultures are obtained to identify infection. Arterial blood gas assessments can define respiratory status and direct oxygenation care.
In general, treatment of respiratory distress is supportive with oxygen therapy provided as needed. Depending on the etiology and severity, continuous positive airway pressure (CPAP) or mechanical ventilation may be needed. Nutritional intake may be oral, gavage, or intravenous depending on the degree of neonatal tachypnea. High respiratory rates can limit effective breastfeeding and raise aspiration risk.
Transient Tachypnea of the Newborn
TTN is benign, self-limited, and stems from slow clearance of fetal lung fluid after birth. Neonates of any gestational age can be affected. However, delivery before 39 weeks’ gestation raises risk, and rates vary inversely with gestational age. Other risk factors are cesarean delivery without labor, male gender, perinatal asphyxia, and large- or small-for-gestational-age birthweight. Maternal gestational diabetes or asthma are others.
TTN is a diagnosis of exclusion. Thus, the evaluation outlined in the last section excludes pathological sources. Treatment is supportive with oxygen therapy as needed. Most TTN cases resolve within 48 hours.
Respiratory Distress Syndrome
This condition stems from surfactant deficiency and has a relatively low incidence at term (Berthelot-Ricou, ...