What Is Persistent Pulmonary Hypertension of the Newborn (PPHN) and Why Does It Happen?

Persistent Pulmonary Hypertension of the Newborn, commonly called PPHN, is a serious condition where a baby’s circulatory system doesn’t make the necessary transition from life inside the womb to breathing air after birth. Instead of the lungs opening up to take in oxygen the way they should, the blood vessels in the lungs stay tight and constricted, just like they were before birth. This means the baby’s blood can’t pick up enough oxygen, even when doctors provide supplemental oxygen.

The condition is life-threatening and requires immediate specialized care in a neonatal intensive care unit (NICU). Understanding PPHN can help families recognize warning signs early and understand the treatment decisions that medical teams may need to make quickly.

How a Baby’s Circulation Normally Changes at Birth

Before birth, a baby doesn’t use their lungs to breathe. Instead, oxygen comes from the mother through the placenta and umbilical cord. Because the lungs aren’t being used yet, the blood vessels in a baby’s lungs stay tight and narrow, and most blood bypasses the lungs entirely through special fetal pathways.

The moment a baby is born and takes that first breath, everything is supposed to change. The lungs expand with air, and the pulmonary arteries (the blood vessels leading to the lungs) relax and widen dramatically. This allows blood to flow through the lungs to pick up oxygen. At the same time, those special fetal pathways close off, forcing all the blood to go through the lungs.

This transition usually happens within the first few breaths and continues over the first hours and days of life. It’s one of the most dramatic physiological changes a human ever experiences.

What Goes Wrong in PPHN?

In babies with PPHN, this crucial transition fails to happen properly. The pulmonary vascular resistance (the pressure and resistance in the lung’s blood vessels) stays abnormally high, similar to what it was before birth. The blood vessels in the lungs remain constricted instead of opening up.

Because of this high resistance, blood takes the path of least resistance and continues to flow through those fetal pathways that should have closed (mainly the ductus arteriosus and foramen ovale). This means blood bypasses the lungs altogether, never picking up the oxygen the baby desperately needs. This bypass of blood away from the lungs is called right-to-left shunting.

The result is severe hypoxemia, which means dangerously low oxygen levels in the blood. No matter how much oxygen is given through a mask or tube, the baby’s oxygen levels stay critically low because the blood isn’t flowing through the lungs to be oxygenated in the first place.

Why PPHN Develops in Some Newborns

PPHN can develop for several different reasons, and sometimes multiple factors are involved:

Underdevelopment of lung blood vessels happens when a baby’s pulmonary blood vessels didn’t develop normally during pregnancy. This can occur with certain congenital conditions like congenital diaphragmatic hernia, where abdominal organs push into the chest cavity and prevent proper lung development.

Injury to blood vessels during or around delivery can occur from events like perinatal hypoxia (oxygen deprivation during labor or delivery), meconium aspiration (when a baby inhales stool-stained amniotic fluid), or birth asphyxia. These insults can damage the delicate blood vessels in the lungs or trigger them to stay constricted.

Infection and inflammation from conditions like sepsis (blood infection) or pneumonia can cause the pulmonary blood vessels to constrict and stay tight. The body’s inflammatory response to infection affects how these blood vessels function.

Structural birth defects including heart defects or congenital diaphragmatic hernia create abnormal anatomy that interferes with normal blood flow patterns and lung development.

Sometimes PPHN occurs without any clearly identifiable cause, which is called idiopathic PPHN. These cases can be particularly challenging because there’s no underlying condition to treat directly.

How Common Is PPHN and Which Babies Are at Higher Risk?

PPHN occurs in approximately 2 out of every 1,000 live births, which translates to about 0.2% of all newborns. While this might seem rare, it means that several thousand babies in the United States are affected each year.

The condition most commonly affects full-term and post-term babies (those born at 37 weeks or later), though it can also occur in late preterm infants (born between 34 and 37 weeks). This is somewhat different from many other serious newborn conditions, which tend to affect very premature babies more frequently.

Risk Factors That Increase the Chance of PPHN

Certain circumstances and conditions make PPHN more likely to occur:

Delivery circumstances:

• Cesarean section delivery, particularly before labor begins (though interestingly, research suggests this may also offer some protection in certain situations)
• Premature rupture of membranes (when the water breaks early, before labor starts)

Newborn medical conditions:

• Respiratory distress syndrome
• Meconium aspiration syndrome
• Pneumonia or sepsis
• Pneumothorax (collapsed lung)
• Congenital diaphragmatic hernia
• Congenital heart defects
• Low Apgar scores at birth

Maternal health factors:

• Maternal diabetes
• Maternal obesity
• Use of nonsteroidal anti-inflammatory drugs (NSAIDs) or certain antidepressants (particularly SSRIs) during pregnancy, especially in the third trimester
• Maternal infections

Understanding these risk factors helps medical teams stay vigilant and prepared, but it’s important to know that PPHN can occur even without any identifiable risk factors present.

Warning Signs and Symptoms of PPHN

PPHN typically becomes apparent within the first 12 to 24 hours after birth, though symptoms can sometimes emerge even later. The signs are usually dramatic and concerning:

Breathing difficulties are often the first and most obvious symptom. The baby may have rapid breathing (more than 60 breaths per minute), grunting sounds with each breath, and visible struggling to breathe. You might see the skin pulling in between the ribs or above the collarbone with each breath (called retractions), and the nostrils may flare as the baby works to get enough air.

Cyanosis is the medical term for a bluish or grayish color to the skin, lips, and nail beds. This happens because the blood doesn’t have enough oxygen in it. In babies with darker skin tones, this may be more visible in the lips, tongue, and nail beds.

Low oxygen levels persist even when 100% oxygen is provided. This is particularly concerning and distinguishes PPHN from other breathing problems. The baby may need increasingly aggressive support to maintain even marginally acceptable oxygen levels.

Low blood pressure and poor circulation may cause the baby to have cold hands and feet, slow capillary refill (when you press on the skin, it takes a long time for color to return), and generally appear pale or mottled.

Low Apgar scores at birth often occur, indicating the baby had difficulty transitioning to life outside the womb from the very beginning.

These symptoms require immediate medical attention. PPHN is a medical emergency, and every minute counts in getting appropriate treatment started.

How Doctors Diagnose PPHN

When a baby shows signs of severe breathing difficulty and low oxygen levels, medical teams move quickly to determine if PPHN is the cause. Several diagnostic steps happen simultaneously:

Physical examination provides the first clues. Doctors assess the baby’s breathing pattern, listen to heart and lung sounds, check oxygen levels with a pulse oximeter on both the right hand and a foot (a difference between these readings can indicate blood is bypassing the lungs), and evaluate the baby’s overall condition.

Pulse oximetry and blood gas analysis measure how much oxygen is in the baby’s blood. In PPHN, these tests show persistent hypoxemia (low oxygen) despite receiving supplemental oxygen. The medical team may also see signs of acidosis (too much acid in the blood), which can occur when the body doesn’t get enough oxygen.

Echocardiogram (ultrasound of the heart) is the definitive test for confirming PPHN. This imaging study can show the right-to-left shunting of blood through fetal pathways that should have closed, measure the pressure in the pulmonary arteries, and rule out structural heart defects that might be causing or contributing to the symptoms. The echocardiogram essentially shows doctors that blood is taking abnormal pathways through and around the heart instead of flowing normally through the lungs.

Chest X-ray helps identify underlying lung problems like pneumonia, meconium aspiration, or respiratory distress syndrome that might be contributing to PPHN.

Getting the diagnosis right is crucial because PPHN requires very specific treatments that differ from other causes of breathing problems in newborns.

Treatment Options for PPHN

Treating PPHN requires a comprehensive, multi-layered approach in a specialized NICU setting. The goals are to get oxygen to the baby’s vital organs, help the pulmonary blood vessels relax and open up, and address any underlying conditions contributing to the problem.

Supportive Care and Monitoring

Before any specific treatments begin, the medical team focuses on creating optimal conditions for the baby’s recovery. This means keeping the baby warm (hypothermia worsens PPHN), maintaining normal blood sugar and electrolyte levels, minimizing stress and handling (which can cause oxygen levels to drop further), and keeping the baby comfortable. Close monitoring is essential because a baby with PPHN can deteriorate rapidly.

Oxygen Therapy

Providing supplemental oxygen is always the first treatment step. Babies with PPHN typically need high concentrations of oxygen, sometimes up to 100%. Oxygen itself helps dilate (relax and widen) the pulmonary blood vessels. The medical team carefully balances providing enough oxygen to support vital organs while avoiding unnecessarily high levels that could potentially cause other problems.

Mechanical Ventilation

Many babies with PPHN need help from a breathing machine (ventilator). The ventilator doesn’t just push oxygen into the lungs; it also uses carefully controlled pressure to keep the air sacs in the lungs open and recruited. Finding the right ventilator settings is crucial. The goal is to maintain optimal mean airway pressure to keep the lungs inflated without causing lung injury from too much pressure.

Inhaled Nitric Oxide Treatment

Inhaled nitric oxide (iNO) is considered the gold-standard treatment specifically for PPHN. Nitric oxide is a gas that, when breathed in, selectively dilates the blood vessels in the lungs without affecting blood pressure in the rest of the body. This is exactly what babies with PPHN need: their pulmonary blood vessels need to relax so blood can flow through the lungs and pick up oxygen.

The treatment involves adding a carefully measured amount of nitric oxide gas to the oxygen and air the baby is breathing through the ventilator. For many babies, the effects are dramatic and happen within hours. Oxygen levels improve, the baby’s color improves, and the work of breathing decreases.

However, iNO doesn’t work for everyone. About 30% of babies with PPHN don’t respond adequately to inhaled nitric oxide, or they initially improve but then worsen again. These babies need escalation to more intensive therapies.

Medications to Support Blood Pressure and Treat Underlying Causes

Babies with PPHN often need medications to keep their blood pressure stable. Additionally, if infection is suspected or confirmed, antibiotics are started immediately. If the baby has signs of respiratory distress syndrome and surfactant deficiency, surfactant replacement therapy may be given.

The medical team also works to correct metabolic acidosis (too much acid in the blood), which can worsen pulmonary hypertension. This might involve adjusting ventilator settings, providing fluids, or giving medications to balance the blood chemistry.

Modern PPHN management has moved away from using paralytic medications (which paralyze the baby’s muscles to prevent them from fighting the ventilator) except in very specific circumstances. Research has shown that paralytics are associated with higher mortality rates, so they’re now used much more selectively.

ECMO as a Last Resort

When all other treatments fail and the baby continues to have dangerously low oxygen levels, extracorporeal membrane oxygenation (ECMO) may be necessary. ECMO is essentially a heart-lung bypass machine that takes over the work of the heart and lungs, giving those organs time to rest and heal.

During ECMO, blood is removed from the baby’s body, run through a machine that removes carbon dioxide and adds oxygen (doing the work the lungs should be doing), and then returned to the body. ECMO requires placing large catheters in major blood vessels, usually in the neck, and the baby must receive blood thinners to prevent clots in the ECMO circuit.

ECMO is a high-risk, resource-intensive treatment that’s only available at specialized centers. It requires a dedicated team of specialists and carries risks including bleeding, stroke, and infection. However, for babies who would otherwise die from severe PPHN that doesn’t respond to any other treatment, ECMO can be lifesaving. Babies typically remain on ECMO for several days to weeks while their lungs heal.

Long-Term Outlook and Prognosis for Babies with PPHN

The outcome for babies with PPHN depends heavily on several factors including how severe the condition is, what underlying causes are present, how quickly treatment begins, and what level of specialized care is available.

Survival Rates and Mortality

Overall mortality rates for PPHN have improved significantly over the past few decades as treatments have advanced. Recent studies report mortality rates ranging from about 7% to 20% in well-resourced hospitals with access to the full range of PPHN treatments, including ECMO. However, mortality can be much higher (up to 36% or even higher in some studies) when PPHN is associated with severe underlying conditions like congenital diaphragmatic hernia or when it occurs in settings without access to advanced neonatal care.

The highest survival rates occur at tertiary care centers (the most specialized hospitals) where neonatologists, ECMO teams, and all necessary resources are immediately available. When PPHN is recognized quickly and treatment is aggressive and appropriate, many babies do survive and can go on to live healthy lives.

Potential Long-Term Complications

While many babies who survive PPHN recover completely, some do experience long-term effects:

Hearing loss is one of the most common complications. The severe hypoxemia (low oxygen) that occurs with PPHN can damage the delicate structures of the inner ear. Additionally, some of the medications used to treat PPHN can potentially affect hearing. Because of this risk, all babies who have had PPHN should receive hearing screening before leaving the hospital and regular audiological follow-up during infancy and early childhood. If hearing loss is detected early, interventions like hearing aids or cochlear implants can be provided at critical times for language development.

Neurodevelopmental delays can occur in some children who experienced severe PPHN. The brain is extremely sensitive to oxygen deprivation, and even temporary periods of low oxygen can potentially affect development. Children who had PPHN may be at increased risk for delays in motor skills, speech and language, learning, or behavioral challenges. Not every child experiences these problems, but regular developmental screening is recommended so any issues can be identified and addressed early with therapies and support.

Chronic lung disease is relatively uncommon but can occur, particularly in babies who needed prolonged mechanical ventilation or ECMO. Some children may have increased respiratory infections or exercise intolerance as they grow.

Feeding difficulties sometimes persist after hospital discharge, particularly if the baby required prolonged intubation. Some babies need feeding therapy or temporary feeding support.

Importance of Follow-Up Care

Because of these potential complications, ongoing medical follow-up is crucial for babies who have had PPHN. This typically includes regular checkups with a pediatrician who knows the child’s history, developmental assessments at specific milestones, hearing tests, and sometimes physical, occupational, or speech therapy. Early intervention services can make a tremendous difference in outcomes when challenges are identified early.

Many children who experienced PPHN as newborns ultimately catch up developmentally and do well, but the journey may involve extra support and monitoring along the way.

The Importance of Specialized Care and Early Recognition

The difference between a good outcome and a poor outcome in PPHN often comes down to how quickly the condition is recognized and how rapidly appropriate treatment begins. PPHN is a condition that can deteriorate quickly, and every hour matters.

Hospitals with level III or IV NICUs that have experience managing PPHN, access to inhaled nitric oxide, and the ability to transfer to ECMO if needed have the best outcomes. When PPHN is suspected or diagnosed at a hospital without these resources, rapid transfer to a specialized center is critical.

For families, understanding what PPHN is and what treatments might be needed can help during a terrifying and overwhelming time. While the condition is serious, advances in neonatal medicine mean that many babies who would not have survived PPHN even a few decades ago can now recover and thrive.

Moving Forward After a PPHN Diagnosis

PPHN represents one of the most challenging transitions a newborn can face, but with expert care, appropriate resources, and timely intervention, outcomes continue to improve. The medical teams treating babies with PPHN understand both the physiological complexities and the emotional weight this diagnosis carries for families watching their newborn fight for every breath.

While statistics and medical terminology can feel overwhelming, what matters most is that each baby receives individualized, expert care and that families have access to the information and support they need during treatment and beyond. The journey with PPHN doesn’t end at hospital discharge; ongoing follow-up ensures that any long-term effects are caught early and addressed appropriately.

If you’re facing a PPHN diagnosis, know that you’re not alone, and that specialized neonatal teams across the country have extensive experience helping babies through this critical condition. Don’t hesitate to ask questions, seek support, and advocate for your baby’s care.