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Transient tachypnea of the newborn (TTN) is a self-limiting cause of respiratory distress due to delayed clearance of fetal lung fluid, typically affecting term or near-term infants within the first few hours after birth.

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https://www.youtube.com/watch?v=mxDZqqadHnM

Etiopathology

Type	Pathology	Mechanism
Normal	Fetal lung fluid is absorbed during labor and by pulmonary lymphatics and circulation at birth	Common after C-section without labor
TTN	In TTN, delayed absorption leads to interstitial and alveolar edema	↓ catecholamines → ↓ ENaC activation → fluid retention

Risk Factors

Elective cesarean section (no labor)
Male sex
Late preterm (34–37 weeks)
Maternal diabetes
Perinatal sedation

Clinical Features

Timing	Clinical features
Onset	• Tachypnea
• Mild retractions, nasal flaring
• No cyanosis/hypoxia (or mild only)
• Duration
Within 1–2 hours of birth	• RR > 60 breaths/min
• Grunting may be present
• Generally well-appearing
• Resolves within 24–72 hours

Diagnosis

Clinical + radiologic diagnosis
Blood gases: Mild hypoxemia, normal or slightly elevated CO₂
Sepsis screen: Usually normal
Lung ultrasound (LUS): Diffuse B-lines, pleural line abnormalities, absence of spared areas