Bronchopulmonary dysplasia is a serious lung condition that primarily affects babies born too early, often requiring prolonged breathing support that can paradoxically contribute to lung damage. Understanding this complex condition helps families navigate the challenging journey from neonatal intensive care to life at home.

Who Gets Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia, often shortened to BPD, affects thousands of premature babies every year in the United States. Estimates suggest that between 10,000 and 15,000 infants develop this condition annually^[5]. The disease shows a clear pattern: the earlier a baby is born and the smaller they are, the higher their risk becomes.

Approximately 40 to 68 percent of babies who weigh less than 1,500 grams at birth (about 3.3 pounds) develop some form of BPD, with the exact percentage varying based on how doctors define the condition^[6]. For extremely premature babies born at or before 28 weeks of pregnancy—when normal pregnancy lasts about 40 weeks—the rate climbs even higher, affecting around 40 percent of these tiny infants^[20].

The condition affects boys more often than girls, and white infants appear to have slightly higher rates than other racial groups^[6]. Babies born after 32 weeks of pregnancy rarely develop BPD^[3]. The disease particularly targets babies who need breathing support for extended periods, with the risk increasing the longer mechanical ventilation or supplemental oxygen is required.

Despite significant advances in caring for premature babies over the past two decades, including better survival rates for extremely early infants, the incidence of BPD has remained stubbornly unchanged^[13]. This persistence partly reflects that more vulnerable babies now survive long enough to develop the condition.

What Causes Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia develops when a baby’s underdeveloped lungs sustain damage over time. Babies are not born with this condition; instead, it emerges as a complication of prematurity and the treatments necessary to keep these fragile infants alive^[2].

When babies arrive much too early, their lungs have not finished developing. The tiny air sacs called alveoli, where oxygen enters the blood and carbon dioxide leaves, are few in number and structurally immature. The airways, called bronchi, are also underdeveloped. These premature lungs cannot function independently, forcing doctors to provide breathing assistance through machines or supplemental oxygen.

The very treatments that save these babies’ lives can injure their delicate lung tissue. Mechanical ventilators deliver oxygen under pressure to expand the stiff, immature lungs and help babies breathe. Over time, this pressure can overstretch the fragile air sacs, causing them to rupture or become damaged^[3]. Higher concentrations of oxygen than what we normally breathe can also harm lung tissue through chemical reactions that create inflammation.

This injury triggers swelling and irritation in the lungs. As the body attempts to heal, scarring can occur. The ongoing cycle of damage and healing prevents normal lung development from continuing. Instead of developing numerous small, healthy air sacs, babies with BPD develop fewer, larger air sacs with thickened walls between them^[6]. The tiny blood vessels that should grow throughout the lungs may also develop abnormally, leading to fewer blood vessels or unusual distribution patterns.

Infections add another layer of complexity. Babies who develop infections during pregnancy or after birth face increased risk of BPD. Maternal infections like chorioamnionitis—inflammation of the membranes surrounding the baby in the womb—can set the stage for lung problems even before birth^[6]. After birth, infections such as pneumonia or sepsis, a serious bloodstream infection, can worsen lung damage.

Sometimes BPD develops even without mechanical ventilation. Other lung problems present at birth, including certain birth defects affecting the lungs or heart disease, can cause similar inflammation and scarring that result in BPD^[4].

Risk Factors That Increase the Chance of BPD

Several factors before and after birth increase a baby’s likelihood of developing bronchopulmonary dysplasia. Understanding these risk factors helps doctors identify which babies need especially careful monitoring.

The most significant risk factor is extreme prematurity. Babies born more than 10 weeks before their due date face the highest risk^[2]. Very low birth weight—less than 2 pounds—also strongly predicts BPD development^[3]. These two factors often occur together, as babies born very early typically weigh very little.

During pregnancy, several maternal conditions increase risk. Mothers who smoke during pregnancy expose their babies to harmful chemicals that can affect lung development^[6]. Pregnancy complications such as preeclampsia or pregnancy-induced high blood pressure also elevate risk. Lack of prenatal steroid medication, which helps mature fetal lungs before early delivery, leaves babies more vulnerable^[6].

After birth, the degree of lung immaturity and breathing problems determines much of the risk. Babies who need mechanical ventilation, especially for extended periods, face higher odds of developing BPD. Those requiring very high pressures to inflate their lungs or high concentrations of oxygen are particularly at risk^[6].

A condition called pulmonary interstitial emphysema, where air leaks from ruptured air sacs into the tissue between them, greatly increases BPD risk^[11]. Heart problems, especially patent ductus arteriosus—an abnormal opening between major blood vessels near the heart—can worsen lung function and contribute to BPD development.

Poor nutrition after birth also plays a role. Premature babies have high nutritional needs for growth and healing, but feeding difficulties are common. Babies who experience significant weight loss in their first days or weeks of life are more likely to develop BPD^[7].

Genetic factors may influence susceptibility, though these are not fully understood. Family history of asthma appears to correlate with slightly higher BPD risk^[6]. Researchers continue investigating whether certain genetic variations make some babies more vulnerable to lung injury or less able to heal properly.

Symptoms and Signs of BPD

The symptoms of bronchopulmonary dysplasia reflect the lungs’ struggle to function properly. These signs vary widely from baby to baby depending on how severely the lungs are affected.

The most obvious symptom is difficulty breathing, medically called respiratory distress^[3]. Parents and healthcare providers notice babies working much harder than normal to breathe. The nostrils may flare open with each breath as the baby tries to pull in more air. Small muscles between the ribs and around the collarbone pull inward visibly with breathing efforts—a sign called retractions^[5].

Babies with BPD often breathe very quickly, a condition called tachypnea^[3]. While newborns normally breathe faster than older children or adults, babies with BPD may take 60, 70, or even more breaths per minute when struggling. They might make grunting sounds with each breath, an instinctive attempt to keep air in their lungs longer.

Changes in skin color signal that the baby is not getting enough oxygen. In babies with lighter skin, a bluish tone may appear on the lips, tongue, or skin—a condition called cyanosis^[3]. In babies with darker skin, these areas may take on a gray, yellow-gray, or whitish appearance. These color changes indicate that oxygen levels in the blood have dropped dangerously low.

Breathing pauses, called apnea, occur when babies stop breathing temporarily^[3]. These frightening episodes may last several seconds and can cause oxygen levels to plummet and heart rate to slow. Wheezing sounds during breathing indicate narrowed airways struggling to move air in and out.

The continuous effort required for breathing exhausts these tiny babies. They may have trouble feeding because coordinating sucking, swallowing, and breathing becomes overwhelming. Poor feeding leads to inadequate weight gain, and babies with BPD often grow more slowly than expected. After hospital discharge, some infants continue experiencing breathing difficulties, especially during viral infections, and may cough frequently or wheeze^[20].

Preventing Bronchopulmonary Dysplasia

Preventing BPD begins before birth and continues through careful management in the neonatal intensive care unit. While not all cases can be prevented, several strategies help reduce risk.

Prenatal care plays a crucial role. Pregnant women at risk of early delivery may receive steroid injections before birth. These medications help speed up lung maturation in the baby, reducing the severity of breathing problems after premature birth^[6]. Treating maternal infections promptly and managing conditions like preeclampsia may help extend pregnancy and give babies more time for lung development.

After birth, healthcare teams work to minimize lung injury while providing necessary breathing support. Gentler ventilation strategies that use lower pressures and volumes of air help protect delicate lung tissue^[11]. Some hospitals use continuous positive airway pressure, or CPAP, delivered through small tubes in the baby’s nose rather than a breathing tube inserted into the windpipe. This less invasive approach can sometimes prevent the need for mechanical ventilation entirely.

Surfactant therapy represents another important prevention strategy. Surfactant is a substance that normally coats the inside of air sacs, preventing them from collapsing. Premature babies often lack adequate surfactant. Doctors can administer artificial surfactant directly into the baby’s lungs, helping them stay open with less pressure needed from ventilators^[11].

Careful oxygen management is essential. Healthcare providers monitor oxygen levels continuously and use only as much supplemental oxygen as needed to keep levels in a safe range. Too much oxygen can damage lungs, while too little oxygen harms the brain and other organs. Finding the right balance requires constant attention.

Prompt treatment of infections helps prevent additional lung damage. Healthcare teams follow strict hygiene protocols to reduce infection risk in the NICU. When infections do occur, appropriate antibiotic or antiviral treatment begins quickly.

Adequate nutrition supports lung growth and healing. Babies with BPD need extra calories because breathing hard burns energy. Nutritionists work with doctors to ensure babies receive enough nutrition, sometimes through feeding tubes if babies cannot take enough by mouth^[4].

How BPD Changes Normal Lung Function

To understand bronchopulmonary dysplasia, it helps to know what happens to normal lung development when a baby is born too early. In a full-term baby, the lungs have spent the entire pregnancy developing intricate structures needed for breathing. By 40 weeks, millions of tiny air sacs have formed, each surrounded by a delicate network of blood vessels.

Premature babies interrupt this development. At 24 to 28 weeks of pregnancy, the lungs have only begun forming air sacs. The number of sacs is far too few for independent breathing. The airways lack the muscular strength and structural support they need. Blood vessels in the lungs are just beginning to branch into the complex network required for efficient oxygen exchange.

When oxygen and pressure from ventilators are applied to these immature structures, physical forces stretch and strain tissues not ready for such stress. The walls of developing air sacs, which should be paper-thin, become inflamed and swollen. Fluid may leak into the spaces between cells. White blood cells rush to areas of injury, releasing chemicals that cause further inflammation^[4].

This inflammatory response, while part of the body’s attempt to heal, actually prevents normal lung development from continuing. Instead of the lungs gradually forming more and more tiny air sacs with thin walls for efficient gas exchange, development goes awry. Fewer, larger air sacs form. The walls between sacs become thick and fibrotic, creating scar tissue rather than delicate exchange surfaces^[9].

The blood vessel network also develops abnormally. Normally, tiny capillaries weave around every air sac, allowing oxygen to enter the blood and carbon dioxide to leave. In BPD, fewer blood vessels grow, and they may be distributed unevenly throughout the lung tissue^[6]. Some areas have too few vessels to adequately exchange gases, while other areas may be overloaded.

These structural changes directly impact lung function. With fewer, larger air sacs instead of many small ones, the total surface area available for gas exchange drops dramatically. Thickened walls between air sacs and blood vessels create a longer distance that oxygen must travel to reach the bloodstream. Abnormal blood vessel development means even the oxygen that does reach air sacs may not efficiently enter the blood.

The result is a lung that struggles to do its basic job. Oxygen levels in the blood may remain low despite babies breathing rapidly or receiving supplemental oxygen. Carbon dioxide, which should be breathed out, may accumulate in the blood because damaged lungs cannot eliminate it efficiently. The airways may become overly sensitive and reactive, narrowing in response to irritants and making breathing even harder.

Some babies with severe BPD develop increased pressure in the blood vessels going to their lungs—a condition called pulmonary hypertension^[2]. The abnormal blood vessel development and chronic low oxygen levels cause vessels to constrict and their walls to thicken, making it harder for the heart to pump blood through the lungs. This complication can strain the heart and further compromise oxygen delivery to the body.