Respiratory distress syndrome (RDS) is a breathing condition that affects premature babies whose lungs haven’t yet produced enough of a slippery substance called surfactant. Without surfactant, the tiny air sacs in a baby’s lungs collapse with each breath, making it extremely difficult to get oxygen into the bloodstream. About 50% of babies born at 26 to 28 weeks develop RDS, while fewer than 30% of those born at 30 to 31 weeks are affected.
Why Surfactant Matters
The air sacs in your lungs (called alveoli) are lined with a thin film of water. That water creates surface tension that naturally pulls the walls of each air sac inward, wanting to collapse them shut. Surfactant is a mixture of fats and proteins that coats these air sacs, reducing that surface tension so they stay open between breaths.
Specialized cells in the lungs begin producing surfactant around the middle of pregnancy, but production doesn’t reach adequate levels until roughly 34 to 36 weeks of gestation. When a baby is born before that point, the lungs may not have enough surfactant to keep air sacs inflated. Each breath then requires far more effort and pressure to reopen collapsed tissue. The lungs become progressively deflated, triggering inflammation and fluid buildup that makes breathing even harder.
Which Babies Are Most at Risk
Prematurity is the single biggest risk factor. The earlier the birth, the higher the chance. Beyond gestational age, several other factors increase the likelihood of RDS:
- Low birth weight
- Maternal diabetes
- Cesarean delivery, especially without labor beforehand
- Male sex
- Oxygen deprivation during or just before birth
Labor itself actually helps prepare a baby’s lungs. The physical stress of contractions triggers hormonal signals that boost surfactant production, which is one reason cesarean deliveries performed before labor begins carry additional risk.
How RDS Looks in a Newborn
Symptoms show up immediately after birth or within the first few hours. The hallmark signs are rapid breathing (more than 60 breaths per minute), a grunting sound with each exhale, flaring nostrils, and visible pulling-in of the skin between the ribs or below the ribcage with each breath. In more severe cases, the baby’s skin may take on a bluish tint from low oxygen levels.
The natural course of RDS is for symptoms to develop within the first six hours of life and progressively worsen over the next 48 to 72 hours before the baby begins to improve. Babies can sometimes sustain the rapid breathing for hours or even days before reaching the point of respiratory failure, which is why close monitoring in the NICU is essential from the start.
How Doctors Confirm the Diagnosis
Doctors typically suspect RDS based on the baby’s gestational age and breathing symptoms. A chest X-ray confirms it. The classic image shows lungs that look hazy or grainy (sometimes described as a “ground-glass” pattern) because so many air sacs are collapsed. In more severe cases, the haziness is dense enough to completely obscure the outline of the heart, and air-filled airways become visible as bright lines branching through the opaque lung tissue.
Treatment in the NICU
The cornerstone of RDS treatment is replacing the missing surfactant and supporting the baby’s breathing while the lungs mature enough to produce their own.
Breathing Support
Most babies with RDS start on CPAP, a gentle stream of air pressure delivered through small prongs in the nose. CPAP doesn’t breathe for the baby but keeps the air sacs from collapsing between breaths. For spontaneously breathing preterm babies with respiratory distress, current international guidelines recommend starting with CPAP rather than immediately placing a breathing tube. Babies with more severe RDS who can’t maintain adequate oxygen levels on CPAP may need a ventilator.
Surfactant Therapy
Surfactant can be given directly into the lungs. Traditionally this meant briefly inserting a breathing tube, delivering the surfactant, and then removing the tube (a technique called INSURE). Newer approaches use a thin, flexible catheter threaded into the airway while the baby continues breathing on CPAP, avoiding the breathing tube entirely. These less invasive methods have shown similar effectiveness in reducing the need for mechanical ventilation.
Preventing RDS Before Birth
When preterm delivery is anticipated, the most effective prevention is a course of steroid injections given to the mother. These steroids cross the placenta and accelerate the baby’s lung development, boosting surfactant production. The optimal window is delivery 2 to 7 days after the steroid course. In studies, this treatment cut the rate of serious respiratory complications from about 12% to 8%, and also reduced the risk of brain bleeding and other complications of prematurity.
Recovery and What Comes After
For many babies, the worst of RDS passes within the first few days as the lungs begin producing surfactant on their own. Babies who still need CPAP support beyond 72 hours typically require care in a higher-level NICU. The total length of stay depends heavily on how premature the baby was and whether complications develop.
The most significant long-term complication is a chronic lung condition called bronchopulmonary dysplasia (BPD), which develops when premature lungs are injured by the combination of inflammation, oxygen exposure, and mechanical ventilation. Among extremely premature infants (born before 28 weeks), BPD is common, diagnosed in roughly 62% in one large study of over 4,400 babies. Nearly all of those babies had RDS initially.
Babies who develop BPD may need supplemental oxygen for weeks or months after leaving the hospital and are more susceptible to respiratory infections during early childhood. Many improve significantly as their lungs grow, but some carry a higher risk of asthma-like symptoms or reduced lung function into later childhood. Babies who recover from RDS without developing BPD generally have a much more straightforward respiratory outlook.
Survival Rates
Outcomes for RDS have improved dramatically over the past several decades thanks to antenatal steroids, surfactant therapy, and better NICU care. In a large population study, RDS-related death rates among preterm infants declined by about 6.5% per year over the study period. The risk remains highest for the most premature babies: those born at 22 to 27 weeks face substantially higher mortality than those born at 28 to 31 weeks, where the rate drops considerably. For babies born closer to term who develop mild RDS, the prognosis is excellent.